Can you compost fish

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Fertilizers have come a long way since the beginning of agriculture. Much of what we are putting in our soil nowadays is a combination of synthetic compounds and chemicals. Fish fertilizers offer an organic solution for effectively providing nutrients to the soil naturally.

The thought of fish fertilizer has some of us gardeners plugging our noses! While it is true that some fish products are unfriendly to the nose, they have a lot to offer the garden. As elementary students we learned of Native Americans like Squanto, showing the pilgrims to use fish (Herring) to fertilize their crops. Some stories suggest that each kernel of corn planted was put into the mouth of a fish and the whole things was planted.

In this article I am going to tell you what fish fertilizer is, the rights kinds of fish to use for fertilizer, and advantages as well as disadvantages of using fish fertilizer.

What Exactly is Fish Fertilizer?

First and foremost fish fertilizer can come from your own catch. As a child I recall a big garden covering most of the backyard, and whatever “junk fish” my father caught throughout the day would more than likely become fish fertilizer.

Next there are the store bought fish fertilizers. One form of fertilizer called fish meal, is made by grinding fish carcasses after most of the oils have been removed. The waste water left over from fish meal can be made into a slime-like gel substance made into fish emulsion which can also be used as fertilizer. Usually only junk fish are used to make fish emulsions.

Next there are Fish Hydrolysates. This form of fertilizer uses whole fish and enzymes to break down the meat and bones of the fish. Afterwards, phosphoric acid is mixed in to help control the enzymes from over digesting the fish, as a result the PH is low and the smell is not as bad as other fish fertilizers.

It is important to know that all fertilizers out there are not selling the same product. Some fish fertilizers use fillers such as seaweed, or ground up sea shells. Make sure you review product information before you buy.

Which Fish are Suitable to use?

Now that you have a background of what fish fertilizer is, let’s take a look at what kind of fish you will be using. When it comes to fish, commercially, there are two options for companies to sell fish.

The first is the fish that people eat. These are usually all the fish that you know about like tuna, sardines, tilapia, and salmon. Now in many instances some of those fish are used in fish fertilizer in some way. This can be from a lack of demand for human consumption, or just the scraps being used like head, scales, and fins. Most of what is used in fish fertilizer is junk fish, scraps, or fish that cannot be consumed by humans because of high toxicity levels. For example menhaden spend a great portion of their lives in water that is contaminated with metals. Therefore they make perfect fertilizer, but not the perfect meal.

Fish fertilizer has many advantages for you and your garden. On top of that, a hidden advantage is the benefits it is doing for the mini ecosystem that is your backyard. Fish fertilizer is simply one of the best ways to grow quality crops and help renew the nutrients in your soil.

Fish fertilizer can also be 100% organic if you are self fertilizing or find the right brand to use. Fish fertilizers are have slower release rates than other types of fertilizer, therefore do not have to be applied nearly as often. When applying fertilizer like fish hydrolysates you are coming about as close as you can to burying a whole fish. Microbes love to feed on the organic matter and this makes for very healthy soil and very healthy plants. While fish fertilizer has a lot to offer there is also a downside.

Some Things to Watch our for

Using fish fertilizer comes with some disadvantages as well. The first thing you will notice is the smell, which unless you have the most sensitive nose in the world, can be manageable. Another common objection is the over fishing and the sustainability of certain fish used. A lot of growers are simply using only waste items and scraps from fish. Still then you can find the right fertilizers to buy just by doing a little research.

Another thing that may be a problem is toxins in fish from polluted waters. Most of these toxins come in metallic form and may even contain mercury. Fish that are more likely to be contaminated are the ones at the top of the food chain. Even still, plants that are not being consumed will have no negative effects but you still should do a little bit of background checking to see what you are putting into your garden.

Go Get Hooked!

Fish fertilizer can be an effective organic way to help grow healthy crops. There are many different forms and brand to chose from. One thing you might consider is catching a few fish and using them as fertilizer to test out the results. Beware of fertilizers advertising fish and really using filler content. Fish fertilizer can be a great way to achieve the maximum potential of your garden. Who knows, after a while you might get hooked on it!

This article was written by Philip Russel. Philip helps to maintain a website that provides information and products for the treatment of Acne. In his spare time he enjoys gardening, and has planted one or two tomatoes over a fish to help his tomatoes grow.
+Shane Genziuk

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Did Native Americans really use fish as fertilizer?

The use of “fish as fertiliser” is one possibility to prevent soil fertility from degradation. After all, whatever you harvest and don’t feed into the local environment, be it people or livestock, and then bring back to the fields as recycling (aka manure) is lost for the next cycle.

The question immediately arising from the fish theory is of course, “isn’t that wasteful?” People might have eaten the fish and got more high quality protein and fat directly, instead of waiting a season for it to be converted to measly plant protein and starches.

But people often do not eat the whole fish, or sometimes a few fish species are caught in nets that aren’t thought of being very edible to begin with. Both options lend themselves to be used in soil improvement. And that is being done now, even with a reference to the claim in question. And now, it also needs to be critically evaluated.

As Wikipedia repeating the myth states for Atlantic menhaden:

Menhaden have historically been used as a fertilizer for crops. It is likely that menhaden is the fish that Squanto taught the Pilgrims to bury alongside freshly planted seeds as fertilizer. Other uses for menhaden include: feed for animals, bait for fish, oil for human consumption, oil for manufacturing purposes and oil as a fuel source.

In the early years of the United States, Atlantic menhaden were being harvested by thousand of ships of fishermen. The Atlantic coastline was lined with processing facilities to quickly transform the fish into a product of worth, typically oil but later fish meal became more popular. Tragedy of the commons set in and the menhaden population began to dwindle. Many of these small companies could not manage, which left only a handful of menhaden fishing companies to remain on the Atlantic coast.

While many sources today claim that the menhaden is inedible, the fish were once consumed as sardines might be, or fried. Maine fisherman, for example, would eat fried pogies for breakfast. The fish that were not sold for bait would be sold to the poorer classes for food.

The reduction fishery processes whole menhaden into fish meal, fish oil, and fish solubles while the bait fishery supplies fishermen with menhaden as bait for key commercial and recreational fisheries. That’s about now and the theory. The historical evidence is more complicated. Real history mixed with pure folklore made it into the textbooks. And the story is a lovely one.

An early article scrutinising fact from folklore:

every year more than three quarters of them have said that they had learned about it in elementary school. Further discussion has brought out two other points: the students generally believe that the practice was not rare but widespread among all the farming tribes, and second, that the Indians taught the American colonists this method of us- ing fish as fertilizer.

The first and rather obvious point to make is that fish, a valu- able food, would hardly have been used as manure unless it was so abundant that people could easily catch more than they could eat. Such abundance normally occurs only along certain coasts, for example that of Peru, or in rivers where fish ascend from the sea to spawn, as in the streams of the Atlantic seaboard of the United States, which in early times were annually visited by enormous numbers of shad, alewife, and other members of the herring family. The interior of eastern North America, which constituted by far the greater part of the aboriginal farming area, was not rich enough in fish to warrant its use as fertilizer.

How old the custom of manuring with fish might be is hard to say. Some of the European “encyclopedias ” and “handbooks ” of agriculture published in the seventeenth and eighteenth centuries speak of the practice as known since “time immemorial,” not a very precise date, but we have definite proof that the method was used in England as early as 1620-and no doubt much earlier, for in 1620 it was described in print by Gervase Markham. We thus know that fields had been manured with fish in Europe before the Pilgrims landed at Plymouth Rock.

Erroneos Citation of Certain Early Sources: There is no question about the use of fish as fertilizer by the colonists in New England in the seventeenth century or the more widespread use of the method in later time. But what needs to be pointed out is that some of the early sources, which have been cited as proof of aboriginal manuring with fish, refer to the English settlers, not to the Indians.

The Negative Evidence: The early record of aboriginal agriculture is indeed a rich one, and, for present purposes, the most significant fact is that in the entire record there is virtually no reference to the use of fish as fertilizer. Furthermore, like Laudonnihre, some of the early observers state positively that the Indians used no fertilizer of any kind. Hariot says of the Secotan in North Carolina, “The ground they never fatten with muck, dung, or any other thing.’’ The Narraganset tribe planted corn without fish, according to John Win- throp (the younger), and similar statements about other New England Indians are made by Edward Winslow and William Wood. The use of fertilizers is denied for the New York Indians by van der Donck, for the Hurons by Sagard, and for the Delaware land Iroquois by Loskiel.’

The Affirmative Evidence: So far as I know, there are only three statements in the primary sources that might be regarded as affirming the aboriginal use of fish as fertilizer. In April, 1621 the Pilgrims of Plymouth colony, according to Bradford, “began to plant their corn, in which service Squanto stood them in great stead, showing them both the manner how to set it, and after how to dress and tend it. Also he told them except they got fish and set with it, in these old grounds, it would come to nothing.”

If Squanto’s statement were a reference to an old Indian custom, it would be inconsistent with native farming methods as we know them from other sources. It will be observed that both Winthrop and Squanto qualify their remarks with the terms “old” and “worn out” lands, the implication being that fish was used, or needed to be used, only on such lands. But we know that the Indians did not try to raise crops on the worn out lands; they quit them. Aboriginal agriculture in the eastern woodland was a system of shifting cultivation: land was continually being cleared, farmed for a few years, and then abandoned; and sometimes, after a period of restoring the soil fertility under forest cover, the old lands might be cleared and cultivated again. The employment of manure or any type of fertilizer was as foreign to native Indian farming as the horse and plow.’”

The Linguistic Argument: Another type of affirmative evidence, or at least affirmative argument, is based on the etymology of “menhaden” and “poghaden” (also called “pauhagen” and “pogy”), which are local names of Brevoortiu tyrannus, an Atlantic fish of the herring family. ‘These names, according to J. H. Trumbull as quoted by G. Browne Goode, are derived from Indian words that mean literally “to fertilize,” and Goode argues that this derivation constitutes “unanswerable evidence” for the manuring with fish in ab- original time.

If a speculative note may be introduced, one may wonder, since the evidence for Indian use of fertilizers is at best rather dubious, whether they had a word meaning “to fertilize.” The missionaries, who compiled many of the Indian dictionaries, studied the aboriginal languages largely for the purpose of translating the Bible, and had the problem of finding Indian expressions for manuring, for example in the parable of the fig tree, “I shall dig about it and dung it” (Luke 13,s). If the Indians had no word for dunging, they soon got an idea for it-suggested perhaps by the missionaries – from seeing the New England colonists manuring their fields with fish. ‘The question is perhaps whether the etymological cart has been put before the horse. Maybe the fish gave its name to manuring, instead of vice versa.

Summary: There is no evidence in the primary sources that the use of fish as fertilizer was a common and widespread practice in any part of native North America. The only affirmative evidence comes from a sharply restricted area in southern New England, but that evidence cannot be accepted as conclusive proof that the practice was aboriginal, for it may have been introduced from Enrope in early Colonial time.

Erhard Rostlund: “The Evidence for the Use of Fish as Fertilizer in Aboriginal North America”, Journal of Geography, 56:5, 222-228, DOI

Did the native American Indians use fish as fertilizer? ‘They’ have. On a small scale, in a confined geography and not since time immemorial. The very detailed and far reaching Squanto-legend has most probably not much explanatory value, as the largest part there seems now to be invented history.

In fact, the many lines of evidence strongly suggest that the invention and use of fish fertilizer by northeastern Indians would have been mal-adaptive, a burdensome land-tethered chore of questionable value for improving corn yields. More adaptive, in fact, was the well documented fallowing technology, especially where beans were planted to “grow up with and against the maize” (Jameson 1909:107). In this way nitrogen became more available to the corn roots (through nitrogen fixation) and the weed area was reduced. The combined beans/corn diet is also higher in available protein and a balance of amino acids, so helps prevent deficiencies caused by corn alone. Given these strategies, might one not argue that the experienced Indians were too wise to adopt the onerous fish fertilizer “solution” taken by the early Pilgrims?
Data for the prehistoric and historic Iroquois suggest the kind of changes that would make fertilizer more adaptive for Indians. These occurred after the presence of traders and expanding colonial settle­ ments had completely transformed the Indians’ culture system and cul­ tivation strategies. Scarce cultivable land and availability of European agricultural technology and staple foods are thought to have brought about permanent settlements (White 1963).

Missionary pressure and acceptance of western values, life on reservations, and replacement of hunting by farming as prestigious male tasks are associated with the adoption of “white agriculture” centuries after contact (Ricciardelli 1963). Similar processual changes appear to have occurred among Algonquian farmers along the coast.
The belief that fish fertilizer originated among North American In­dians, and was communicated as such by Squanto to the Plymouth settlers, has achieved the status of an unquestioned legend and is there­fore difficult to challenge. Responses from my original study confirm both a worldwide interest in the topic as well as the legend’s cherished status in this country.

Nevertheless, while Squanto was unquestionably an important historic figure and did contribute substantially to the Pilgrims’ survival, the belief that fish fertilizer was a “manner of the Indians” because Squanto knew about it should be revised. The current evidence indicates that his advice at Plymouth is best viewed as a special example of culture contact dynamics, one in which a native culture-bearer conveyed a technological idea from one group of Europeans to another.
Lynn Ceci: “Squanto and the Pilgrims: On Planting Corn ‘in the manner of the Indians'”, in James A. Clifton (Ed): “The Invented Indian Cultural Fictions and Government Policies”, Routledge: London, New York, 1990. (pp 71–90)

Personal commentary:

The story as read on Wikipedia about Squanto is not credible. The lifecycle of seasonal plants requires nutrients, that can be found in fish. But burying a whole fresh fish is mal-adaptive for other reasons than just wasting difficult to transport inland animal protein. It doesn’t get transformed into plant nutrients in the best way and time to be of much use. Parts of it or processed fish are another story. But one fish alongside the seeds is more of magical or symbolic benefit then bringing really plant usable soil fertility in a growth related timely manner for the season.

More detail about the Life of Squanto in Jerome P. Dunn: “Squanto Before He Met The Pilgrims”, Bulletin Of The Massachusetts Archaeological Society, Volume 54(1),1993 38–42. (PDF)

These details lead some researchers to summarise the story very bluntly:

Squanto & Fish Fertilizer
A familiar Thanksgiving story is that the Native American, Squanto, showed Pilgrims the Native American method of fertilizing corn with fish. It is true that Squanto showed the Pilgrims how to use fish as fertilizer. However, there is no good evidence that Native Americans east of the Mississippi River ever used any form of fertilizer (Ceci 1975; Hurt 1987; Rostlund 1957). Instead, Native Americans practiced shifting agriculture and simply moved on to a new tract of land when the natural soil fertility ran out. They also interplanted corn, beans and squash, which they called the three sisters (Marturano 1995). The nitrogen-fixing beans provided some nitrogen for the corn and squash.

How then did Squanto know about fish fertilizer?
Squanto knew because he was kidnapped by a British sea captain in 1614 and spent seven years in Spain, England, and with British colonists in Newfoundland before arriving at Plymouth on 16 March 1621 (Hurt 1987). Somewhere in his association with Europeans, Squanto learned of fish fertilizer. Thus, Squanto merely taught the Pilgrims a European agricultural practice that had been known since ancient times. The use of dead bodies as fertilizer is mentioned in the Bible and was expressed poetically by the 11th century Persian poet Omar Khayyam (Tisdale & Nelson 1975):

I sometime think that never blows so red
The rose as where some buried Caesar bled;
That every hyacinth the garden wears
Dropt in her lap from some once lovely head.

As a modern Massachusetts gardener has found (Moss 1975), use of fish fertilizer seems impractical where wildlife abounds. Skunks, raccoons, dogs and other animals dig up the rotting fish and damage or destroy the planting.
David R. Hershey: “The Truth behind Some Great Plant Stories”, The American Biology Teacher, Vol. 62, No. 6 (Jun., 2000), pp. 408-413. (jstor)

Love Apple Farms

Myth #1: You can’t compost animal products

Well, I’m here to tell you that you can indeed compost animal products. Look at this beautiful blue fin tuna head. It came from Manresa, and would have ended up in the dumpster had it been at just about any other restaurant. But here at Love Apple Farm, we take all the fish waste back to the garden and compost it. This tuna head was gigantic; it’s hard to get a proper perspective on its size, but if you check out the head of romaine lettuce next to it, you can appreciate how big it was.

You can compost animal carcasses as well. I was initially appalled at this revelation when Harald Hoven, my professor at the Rudolph Steiner College explained how they regularly put road kill carcasses in their biodynamic compost piles. But after helping the class turn a pile that had six months before contained eight dead opossums, I became a believer. The only discernible residue of the opossums in the now perfectly black and crumbly compost was small bones and skulls. Harald explained how they sprinkle a good handful of lime on the carcass to help get the decomposition started.

I haven’t quite got up the nerve yet to compost any dead animals, mostly because the restaurant keeps us in a pretty steady stream of fish parts. We keep my dogs and the marauding racoons out of the fish-infused piles by making sure there is plenty of plant waste put immediately on top of and around the stinky bits. Once enough plant residue is properly layered on the fish and then compacted down by stomping on the pile (more on that later), the decaying fish smell isn’t noticeable to humans. As far as the curious critters are concerned, I further ensure they don’t dig up the pile by having high wire sides to it, and covering it with a tarp.

Fish products in the compost pile make extra nutritious finished compost. You all know the benefits of fish emulsion on plant growth; it’s very high in nitrogen. Having the decomposed fish in the compost just adds another healthy element to this all-important soil amendment. And let me tell you, the quality of Manresa’s seafood scraps couldn’t possibly be any better. They indeed help us grow better vegetables.

Stay tuned for more compost myths debunked this week.

How to Use Fish Waste Fertilizer

Fish parts, such as guts, bones and heads, are rich in nitrogen, potassium, phosphorus and trace minerals that support root and foliar growth as well as healthy, abundant blooms. Liquid fish emulsion, which is sold in stores as an organic fertilizer, is made from fish parts not used by processing plants. Regardless of its form, using fish waste in the garden is as easy as burying leftovers from a catch or from a fish dinner in the soil or compost heap.

Fish Emulsion

Dilute liquid fish emulsion before using it on plants. To water individual trees, plants or potted plants, use a tablespoon of emulsion per gallon of water. For a foliar spray, mix 1 or 2 ounces of fish emulsion into a gallon of water and spray it onto leaves or grass. Apply in morning or evening when temperatures are cooler.

Feed sensitive and hot weather seedlings, such as tomatoes and peppers, with a teaspoon of undiluted fish emulsion when you transplant them. This helps protect roots and give them a nutrient boost. Apply to more mature growth in the spring as well when their growth is more active.

Make your own fish emulsion by boiling leftover fish parts in a large pot with just enough water to cover the waste. Liquidize it in a blender, and use this mixture as you would commercial fish emulsion.

Use Fish Waste

Bury fish guts, heads and other parts in the garden near plants or trees that need an extra nutrient boost. Place the fish waste at least a foot below the soil to discourage wildlife and pets from digging it up and try to avoid disturbing the root system.

Bury a dead aquarium fish in a houseplant instead of flushing it down the toilet. Make sure the plant is out of reach of other house pets.

Compost fish waste in an outdoor compost heap by burying the fish at least two feet deep in the compost pile. However, you can not disturb the fish waste, so this option is not for compost heaps that require regular aeration. This method works well for a small amount of fish waste. For larger amounts, turn the fish waste into a liquid fish emulsion. (see Section I)

Use fish waste water as a nutrient-rich fertilizer. Water plants with waste water from freshwater aquarium and fish pond water changes or water you’ve used to wash fish while cleaning them.


Decomposition in fish, such as tuna and mahi-mahi, is detected by organoleptic evaluation. It is also indicated by elevated histamine levels in the muscle tissue. The presence of 50 ppm (5 mg/100 g) or more histamine is indicative of decomposition in these fish whether or not organoleptic examination detects decomposition.

Histamine forms postmortem by bacterial action on the amino acid, L-histidine. Histamine is heat-stable and survives thermal processing. It is therefore a useful indicator of decomposition in scombroid and certain other fish because odors that normally signal decomposition to the organoleptic analyst may be modified, reduced, or eliminated by thermal processing.

In addition to being an indicator of decomposition, when ingested at sufficiently high levels histamine causes scombroid poisoning. Cases of scombroid poisoning have been traced to the consumption of raw, frozen, and canned tuna and raw and frozen mahi-mahi. The term, “scombroid fish poisoning,” developed because fish of the families Scombridae and Scomberesocidae are implicated in instances of histamine poisoning derived from decomposition in these fish. Tuna and mackerel are most frequently involved in instances of histamine poisoning, but this fact may be partly the result of the rate of consumption of these species worldwide.

From 1977 to 1981 there were 68 outbreaks of scombroid poisoning involving 461 illnesses. In the United States (U.S.), from the period of 1968-1986, a total of 188 outbreaks of histamine poisoning were reported. Certain nonscombroid fish such as mahi-mahi (Coryphaena hippurus) may also be involved in histamine poisoning. In March 1980, the Centers for Disease Control and Prevention stated that mahi-mahi accounted for 40 percent of the scombroid poisoning outbreaks reported in the U.S. Bluefish (Pomatomus saltatrix) have been responsible for several outbreaks in the U.S. and have caused at least one outbreak in Australia. Outbreaks have also occurred in the U.S., implicating pink salmon, redfish, yellowtail, marlin, and amberjack. Outside the U.S., pilchards, herring, anchovies, bluefish, and sardines have been involved in a number of cases. Sardines and pilchards have become a major source of histamine poisoning in Great Britain. Japan had an outbreak associated with black marlin, and anchovies have been implicated in single incidents in Japan, the U.S. and Great Britain.

The agency’s use of histamine levels as reliable indicators of decomposition is based primarily on agency experience with tuna and mahi-mahi. However, as noted above, other species have been implicated in a significant number of incidents of histamine poisoning. These other species also contain high levels of free L-histidine in their muscle tissue and are known to form histamine as they decompose. Therefore, on a case by case basis, when these other species contain levels of histamine of less than 500 ppm but equal to or greater than 50 ppm, the agency may determine that these fish are decomposed. In these instances, FDA determination that the fish is decomposed may be based not only on the histamine level but also on other scientific data, including the presence of other amines associated with decomposition in these fish.

In addition, FDA intends to use the action level for canned tuna of 500 ppm in considering whether fish of other species that previously have been implicated in histamine poisoning outbreaks are adulterated.


The following represents criteria for recommending legal action to CFSAN/Office of *Compliance*/Division of Enforcement (HFS-605). Histamine values used to support a recommendation, at a minimum, need to be accompanied by the information described in the compliance program or assignment. The appropriate program or assignment will provide correct information on: sample size, number or subsamples to examine preparation and analytical procedure. Submit the original and check results with the recommendation for action.

Criteria for recommending regulatory action for the presence of decomposition in canned tuna are usually based on a sample size of 24 cans (subsamples). In deciding whether to authorize seizure, HFS-605 will expect to see that a minimum of two subsamples must contain evidence of decomposition when up to 24 cans, but not necessarily all 24 cans, are analyzed. For example, to support a recommendation for regulatory action, if 18 cans are analyzed, two cans found to contain evidence of decomposition. However, when more than 24 cans are analyzed, the number of cans that would be expected to contain evidence of decomposition to justify regulatory action is proportionately higher. For example, if 36 cans are examined, HFS-605 would expect that 3 cans be found to contain decomposition to support a recommendation for regulatory action. Similarly, for raw and frozen fish, a minimum of 2 subsamples would generally be expected to contain evidence of decomposition when up to 24 subsamples are examined if regulatory action is to be authorized.

Decomposition, tuna and mahi-mahi

  1. Histamine level equal to or greater than 50 ppm in at least two subsamples by both the original and check analyses.
  2. Organoleptic evidence of decomposition, except honeycombing in canned tuna, is found in at least two subsamples by an analyst qualified in organoleptic testing and the findings are confirmed by a national expert in organoleptic testing.
  3. Honeycombing is found in two subsamples by an analyst qualified in organoleptic testing and confirmed by a national expert in organoleptic testing.

Decomposition, species other than tuna and mahi-mahi

Samples of fish previously implicated in instances of histamine poisoning found to meet criterion a. or b. (below) may be considered adulterated within the meaning of 21 U.S.C. 342(a)(3) when supported by other scientific data.

  1. Histamine level equal to or greater than 50 ppm but less than 500 ppm in at least two subsamples by both original and check analyses.
  2. Organoleptic evidence of decomposition is found in at least two subsamples by an analyst qualified in organoleptic testing and the findings are confirmed by a national expert in organoleptic testing.

Danger to Health

Samples of fish implicated in an instance of histamine poisoning that have been found to meet either criterion a. or b. (below) should be considered adulterated within the meaning of 21 U.S.C. 342(a)(1).

  1. Histamine level equal to or greater than 500 ppm in one subsample by both the original and check analyses, or
  2. Documented evidence of an illness associated with the fish irrespective of histamine content.

*Material between asterisks is new or revised*

Issued: 10/1/80
Reissued: 7/1/81
Revised: 10/30/89, 3/95, 7/26/95, 5/2005
Updated: 11/29/2005

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Submit comments on this guidance document electronically via docket ID: FDA-2013-S-0610 – Specific Electronic Submissions Intended For FDA’s Dockets Management Staff (i.e., Citizen Petitions, Draft Proposed Guidance Documents, Variances, and other administrative record submissions)

If unable to submit comments online, please mail written comments to:

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All comments should be identified with the title of the guidance.

An aquarium is a place where you would not want to create chaos. Fish are sensitive creatures and even the slightest change in water quality, pH, temperature, etc. can startle them and at times or even kill them. So why take the risk of losing them by leaving their excrements unattended?

How to get rid of fish poop in the tank? Fish poop can be cleared by simply scooping them out of the fish tank. Fish excrements will naturally perish thanks to the Nitrogen cycle which breaks it down into ammonium and nitrate. However, rely on this fact or just scooping it will not solve the poop problem in your fish tank. A scheduled weekly cleaning routine is the key.

However, as we know just scooping it regularly will not solve the problem as there is a lot more to worry about afterward.

What is the difference between fish poop and other waste materials in tank water?

Two types of waste materials are usually found in fish tanks; organic ones and inorganic ones. Fish poop belongs to the organic category.

Organic Waste

Organic waste materials are naturally perishable most of the time. They do not require manual labor to be cleared if they are in an environment within which, they can decompose and mix with the soil or in some cases, water.

Inorganic Waste

Inorganic waste materials, on the other hand, are not able to decompose by themselves. Outside stimuli or interference is needed to decompose these types of substances. Under normal conditions, they will not mix with the soil or water. Even if they do, they will not fully breakdown or decompose, which will negatively influence the ecosystem of the environment they are in.

Being organic in nature, the fish excrements can easily dissolve into the soil of the fish tank. The poop goes through a Nitrogen cycle which breaks it down into ammonium and nitrate.

Apart from fish poop, uneaten and leftover fish food pellets are also treated as organic waste materials inside the fish tank. But unlike fish excrements, the food pellets do not undergo any natural organic cycle that dissolves them into the soil or water of the tank.

Besides, there might be other organic waste materials that fall into an open fish tank like pollen, dust particles, small insects, etc.

Inorganic wastes are also found in tank water. They mainly enter the tank from outside. Such wastes may include everything from small pieces of paper to even large Ping-Pong balls. This type of waste will not perish naturally.

Plastic, for instance, will not decompose. They will outlast you and your fishes. Hence, such waste substances need to be dealt with separately.

In order to prevent your fish tank from becoming a waste dump, be sure to clean it at regular intervals. Schedule weekly cleanups, your best tip for today.

How much poop is OK and what is a lot of fish poop in the tank?

Excrements released by the fish inside the aquarium releases ammonia into the water over time which, if not kept under control, has the ability to destroy the ecosystem inside the tank.

The natural Nitrogen cycle helps avoid such a situation. However, if the nitrate and ammonia levels get too high, the natural cycle will not be enough to keep the situation under control.

Hence, it is in your best interest to maintain the tank with proper cleaning mechanisms such that excessive poop does not accumulate inside the tank.

How many times a day does a goldfish poop?

On average and under suitable conditions (environment, water, temperature, quality of food), a goldfish can produce poop 8 times in a single day. Sometimes, this number can vary from five to eight.

It is not, however, possible to calculate the exact number of how many times a goldfish defecates each day. This is because of the digestive system of the goldfish.

Goldfish tend to defecate a lot as they have no stomachs. No stomach means no muscular movement to breakdown complex food substances into the absorbable matter. Thus, no process of assimilation is seen. This results in their habit of producing waste more frequently than any other fish.

The more food, the more waste fish can produce.

The amount of poop is greatly dependent on the amount of food they consume. The more their consumption of food, the more waste they can produce. Size, water temperature, pH levels, etc. also affect the goldfish’s food intake.

They process the food very quickly as they consume it. A goldfish requires feeding 3 times per day the volume of one of their eyes.

What happens to fish poop in the aquarium?

Fish poop within your aquarium will take some time to settle down. Prior to this, they are most likely to float around inside the tank.

You will often find your fishes nibbling at the poop floating inside the tank. Fishes have the tendency to eat up whatever is floating around them but at the same time, they also spit out any non-food items back into the water.

Fish poop breaks down over time into ammonia and then into nitrate. The aquatic plants inside your fish tank can consume both the ammonia as well as the nitrate. The Nitrogen cycle that takes place inside your tank is what makes all this possible.

If left unattended in a tank where there is no soil/gravel substrate for the poop to mix itself with, the excrements will simply be sediment at the tank bottom. Over time, the poop will create a pungent and rather toxic smell inside your tank.

This results in a rise in temperature and a change in pH levels, thus, destroying the harmony that exists within your tank’s ecosystem.

What color is fish poop?

Under natural circumstances, the color of your fish’s poop depends on its species and the diet it is consuming. The color pigments from the food can often dissolve within the fish intestine and the excrements of your fish will be found to have a color similar to the color of the food it is being fed.

Healthy fish poop is usually the color of the food it is being fed or slightly brownish, like sand. Thin, white colored poop is a sign of internal infection.

If you observe such whitish excrements from your fish, you should be slightly worried and if possible, get your fish checked or bring alterations in its diet.

Diarrhea in fish can be identified as a brownish tinge in the tank water. Low-quality food with high amounts of toxins is usually responsible for diarrhea.

Is fish poop good for aquarium plants?

No, fish poop is not good for aquarium plants.

Common sense might suggest that like other excrement, such as manure, the excrements of your fishes are also good for the plants growing inside your fish tank. But no, it is in fact just a rough belief.

Our body throws out whatever it is it cannot digest or absorb into the body itself. The case is the same for almost every other animal. Fish is no different to this phenomena. Like humans and other living organisms, fishes produce waste as well.

Nitrogen is a waste product most animals produce, including fishes. Now nitrogen in itself is helpful for plants as it helps plants to grow. In fact, urea fertilizers are mostly nitrogen. But the nitrogen being produced by your fish poop is not reaching the plants directly.

Inside the tank water, there is the possibility that nitrogen will manage hydrogen molecules to bond with it and then produce ammonia, which is dangerous for your aquatic plants and fishes.

Ammonia can mess up the respiration process. This, in turn, will shift the ecosystem inside your fish tank upside down.

Besides, the fish poop cannot even reach the soil substrate in your fish tank if there is a thick layer of pebble or gravel inside the tank, overlaying on top of the soil substrate. Apart from a few species of aquatic plants, most of them grow on the soil and not on the hard surface of pebbles. Thus, the poop may not be able to reach the roots of the plants to nourish them.

What Are Cleaning Techniques, Methods, Secrets In Poop Reducing And Removing From Fish Tank?

Prior to cleaning the tank, the first and most important task at hand is to relocate your fishes to a temporary location as you prepare to clean their home.

This can be easily achieved by storing your fishes in polythene bags or another fish or glass tank. While doing so, make sure that the water your fishes are going into is coming from their aquarium, the one you are about to clean. Otherwise, if fishes are exposed to water of different quality (such as varying in temperature or pH levels), they might fall sick or even die.

Next, remove the decoration props inside the aquarium one by one and clean them individually. Use disinfectants as required but be sure to rinse them with adequate water afterward.

To clean the poop, you can just drain the tank with a pump or scoop away the excrements. Afterward, remove the gravel or pebble layer and wash it with soap or detergent, followed by proper rinsing with sufficient water.

For keeping the number of fish excrements under control naturally, you can opt of a planted aquarium with a soil base, layered off with a gravel or pebble top. Make sure the gravel layer has small holes in between them for the poop to settle down into the soil.

Naturally, this should allow the poop inside the fish tank to mix up with the soil. However, it is still a good idea to scoop away the gravel surface from time to time to remove the excess poop. Otherwise, the tank water might smell and take up a faded color.

Do algae eaters eat fish waste from the bottom of the tank?

No living creature eats excrements, at least not willingly. Algae eaters are no exception to this habit.

Some eaters do, however, consume fish poop inside the tank, but spit it out instantly the moment their senses can identify the substance as non-consumable matter. Algae eaters will be able to keep the tank clean from algae only.

An algae eater often referred to as Algivore, is a common name for many bottom-dwelling, algae-eating aquatic species that feed on algae. Some of the common and most popular freshwater algae eaters in aquariums include small fishes, shrimps, crabs, and snails.

Before deciding on whether you want to have algae eaters in your fish tank, there are a few things you need to consider.

Select such an eater that it will be compatible with the other fishes and organisms in your fish tank. Also, take the size of your fish tank into a note. That will allow you to decide the number of eaters you would need inside the tank.

And so, as you can see, having fishes inside an aquarium is no easy hobby, especially when you need to consider cleaning their excrements. Not only is it a tedious job, but it also requires quite the precision.

Clearing excrements that came out of fish is by all means, not rocket science. However, if you really want to be involved with this hobby and willing to take good care of your fish, you might as well understand the points mentioned above and try to practice accordingly. There is nothing called being too careful.

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