There are three classes of piscivore that may need to eat live fish food. If you donít know already, a piscivore is an animal that primarily eats fish, so this term also includes animals other than fish. There are opportunistic piscivores, facultative piscivores and obligate piscivores.
The difference in the piscivore variations will determine whether or not the piscivore will be receptive to taking other variants of fish food. The opportunistic piscivores can readily be trained to take other types of food rather than live fish. Facultative piscivores may have a harder time adapting to other variants of fish food like frozen fish food or freeze dried foods. Finally obligate piscivores must be fed live fish. They rely on visual indicators as well as other indicators to strike. These indicators are not easily duplicated in things that are not live fish.
Freshwater stonefish, pike livebearers and needlefish are all species of obligate piscivores. If these are species of fish that you choose to keep in your tank then you should be prepared to feed them live feeder fish. If you have a community tank that is producing fry you should be aware of the piscivores in your tank.
The advantages of feeding live fish are simple. Obligate fish-eating fish will not be trained to take other foods. For the other types of piscivores this provides an opportunity to forego training them to take other types of food. Also feeder fish are regularly kept in stock so that predatory fish are sure to have a constant source of food. If a variety of feeder fish species are fed to the fish it can be a very good diet.
The unique disadvantage in feeding live fish food in the form of smaller fish like guppies and goldfish is that the cramped conditions these fish are kept in often make breeding grounds for parasites, disease and other forms of bacteria. There are ways to avoid this like breeding your own livebearers. When breeding livebearers it is often the case that a portion of the fry will be undesirable. Using them as feeder fish provides a good alternative.
Other variations of live food can also be used. Feeder fish are not the only source available. Many fish will gladly accept bloodworms, shrimp, earthworm segments and crickets as a form of live food. These live foods can be great to feed the fish and can provide fantastic sources of nutrition combined with things like flake food and other forms of food.
The problem with many of these alternative forms of live fish food is that they can be seasonal and they usually do not have a lengthy time in which they can be used. Blood worms for example have a life of about 10 days in which they are usable in the feeding of aquarium fish. They may not be useful for those having smaller aquariums where they may not be eaten quickly. Earthworm segments may provide a good alternative for mid-range feeders while crickets and others may be better suited for top feeders. Most bottom feeders are not solely carnivorous and will take a variety of food sources.
The choice of predatory aquarium fish should be made with great consideration and care. The most important thing to consider is whether or not you are willing to feed an obligate piscavore exclusively feeder fish. If you are unwilling to do so you may need to choose another species of fish. Keeping happy healthy fish should be the goal of feeding them any variant of live fish food. If the food that the fish are eating is not providing them with the nourishment that they need then alternative sources of food are necessary.