Failing to remove or convert waste in any closed system will result in disease, reduced resistance to parasites and other causes of fish mortality.
Ken Durrett says:
You might be able to find an anti-bacterial medicine to treat the fish; but that will neither eliminate the root of the problem nor prevent further infestation. The solution is to be found in establishing and maintaining high water quality by eliminating the organic loading in the water. Loading factors are basically the unavoidable consequence of fish fecal and urea, unconsumed feed and fish respiration.Take a moment to imagine what life be like for us humans if you and I were were forced to live in a small, closed room with no toilet facilities and little or no fresh air coming in? In a very short time, we would be living in a filthy, miserable, disease-infested room, wouldn't we?
Often, that is exactly how it is for fish in a farming environment. They are confined in a relatively small, crowded space with thousands of other fish who are using-up a limited amount of oxygen and who are all "pooping" in their living space and even fouling their source of oxygen. Water quality instantly begins to be contaminated; and the more contaminated it gets, the more unhealthy it becomes. The organic material in the water becomes both a breeding ground and nutrient source for a wide array of pathogenic agents (such as hookworm).
Obviously, common sense tells us that the best thing to do is to get rid of the contaminants - the organic waste that is loading-up the water. Right? Well, that begs the question: How do you do that and do it affordably or economically?
I believe that the best way to do it is the way that God created for it to be done - naturally. By "naturally," I mean: Using the same method that God uses in nature. Enzymes and bacteria are what were created to breakdown organics in nature. The problem is that we often create situations that are unnatural and out of balance. When a situation is out of balance, there is a shortage of the good species of microbes and an abundance of the bad ones. There are over 80,000 species of bacteria that have been identified and only 2% of those are harmful or pathogenic. We cannot live without bacteria. We must have them. The problem is that, eventhough only 2% of them are bad, we have a tendency to get things out of balance and create an environment that helps the harmful species to thrive while starving-out the good ones.
So, what we need to do is to find a way to reverse that process. The way to do that is by introducing the right species of good microbes which will fight back and take control of the situation by eliminating the contaminants that cause a problem. The key is having the right enzymes and bacteria to do the job. The reason why that is so important is the fact that each microbe does only ONE thing and nothing else; but it does that one thing VERY well.
For instance, if a "bug" (a euphomistic term in the industry which refers to bacteria) digests fat it will have zero affect on protein, cellulose or starch, etc. - and vice versa; but it will gobble-up fat like it was homemade ice cream. If you introduce a combination of many different, but specific, bugs covering a broad spectrum of organic wastes (lipids, protein, cellulose, starch, etc), the result will be the creation of a healthy environment which is favorable to the good microbes and fatal to the bad ones. The pathogenic agents will be starved-out as the good ones out-compete them for their food source. The loading factors will be digested and the water quality will be restored, creating a healthy environment for the fish to thrive.
See also: