We have all heard the term big fish eat little fish and small fish big pond, but within fishkeeping circles, the underlying point that some fish are indeed predators and feed on other fish remains controversial. There are two main objections in the fishkeeping hobby when it comes to feeding live feeder fish. The first is that the use of live ‘feeders’ is cruel, the suffering inflicted on the small fish in no way justifies their usefulness as food. The second objection is that the use of feeder fish isn’t just unethical, but actually harmful, endangering the health of the predatory being kept. In fairness, very few Fish Keepers use live fish as food. But there are a few Fishkeepers keeping big, predatory species that will feed their large fish feeder fish.
On the one hand, using live feeder fish can be considered an easy and convenient way to feed carnivorous animals such as pet snakes, fish, and birds of prey. However, on the other hand, it raises concerns about animal welfare and the ethics of causing unnecessary suffering to animals. Feeder fish are often kept in overcrowded conditions, which can cause stress, disease, and death. They are also frequently shipped long distances and subjected to adverse conditions during transportation. In addition, feeding live prey to animals can cause unnecessary suffering, as the prey may be attacked multiple times before being eaten, and death may not be instantaneous.
Goldfish are especially popular as feeder fish, being cheap and relatively large, but they are actually among the worst of all prey species for most predatory fish. They are fatty and rich in a chemical called thiaminase, an enzyme that destroys the essential nutrient thiamine (also known as vitamin B1). Consuming too much thiaminase will eventually cause liver failure in predatory fish. Not to mention that cold fish cannot process too much fat, which in itself can cause all kinds of health issues for your predatory fish. Many people would argue that these fish also eat other fish in nature, but that is only half the truth. In nature, predatory fish are opportunistic feeders, so they will eat insects, amphibians, fruits, and yes other fish.
By contrast, fishkeepers taking the time to train their predatory fish to take a selection of frozen foods supplemented with pellets or flakes can guarantee that their fish will receive a varied diet that will keep their fish healthy throughout their lifetime. For the most part, predatory fish are easy to train because it is in their nature to try all sorts of different food items when they get hungry. All you as a fishkeeper need to do is provide them with a variety of dried and frozen foods and see which ones they like. Often, starving your predatory fish for a few days helps to whet its appetite, encouraging it to try whatever foods you put on offer. Large predatory fish can easily manage without food for a week or two.
