Selection of diet for fish, begin by examining the nutritional requirements of each specific species.
For a start, it should be noted that fish, like all other animals, are divided into several trophic groups.
Animal-eating. eat food of animal origin. This group includes predators (eat fish, frogs, etc.), insectivores and eating both. Typical predators are piranhas. The latter include labyrinths, discus, scalar and almost all small cichlids (apistograms, parrots, lamprologusy, etc.). Representatives of the third group are American cichlids (astronotus, tsikhlazomy, Akara). All these representatives get used to eating sliced fish pieces (cod, pollock, navaga, raw pink salmon is useful for enhancing the red color), squid and other seafood. Freshwater fish is better not to feed because of the possibility of entering into the aquarium parasites. You can offer lean beef, heart and boiled liver, but not often. From the constant consumption of meat of warm-blooded animals, fish can become fat. Food is cut into pieces so that the fish swallows it easily; but remember, very small fish food is unnerving. Piranhas can be given large pieces, they tear them themselves. Also, these fish (except piranhas) willingly eat all standard feed for aquarium fish.
Herbivorous. fish feeding on various parts of plants. For aquarium fish, this group is very relative. Almost all the fish bred in an aquarium do not refuse, but on the contrary, they even love animal food very much.
Omnivores (polyphages). it is this group that includes almost all types of aquarium fish. They fit all the usual feed. Live food (bloodworm, coretr, tubule, daphnia) are closest to the natural food of fish, but I would advise them to freeze, so as not to cause disease-causing organisms. No matter how good the live food is, it cannot satisfy all the needs of the fish organism. In captivity, we can offer fish 5-6 types of food, while in nature the species composition of the organisms eaten can reach hundreds. You can diversify the diet already mentioned above seafood, fish, beef and liver. Feed for fish, as a rule, already contain herbal supplements, but if the need arises, you can use flakes of rolled oats, scalded lettuce, spinach, cabbage; especially for herbivorous piranjev (metinis, etc.), Malawians, chain catfish, synodontis, goldfish.
The more varied the diet, the healthier the fish. Even the best food can not be complete; something in it, but not enough. Many feeds are considered complete, they are packed with everything that the fish needs, but this is dry food. Can a person eat sandwiches alone and keep his stomach healthy? Also, fish, although sometimes in need of natural feed, if the feed is the main component of the diet.
Some fish, such as discus, are difficult to get used to changing feed. In this case, you can add less fastidious fish. Seeing how she eats, the pickup will also start to eat, the pack instinct will work.
One more question, how much to feed? The rate of feeding is chosen empirically, the fish should eat food in 5-7 minutes. Feed is given in the amount of 5% of body weight. If there are a lot of fish in the aquarium, let’s feed in several places so that we can eat everything. Otherwise, they will feed the most nimble, and there will not be enough more calm. It is better to feed the fish twice, but it is also possible to feed one; fry are fed more often. Growing fish eat about 30% of body weight per day.
Fish should not be overfed. Sustained food reflex says about the well-being of fish. So no need to regret the fish and give food at their request. Adult animals should be a little hungry. In nature, a fish spends 70-80% of its time searching for food, often swimming long distances, but in an aquarium its movements are limited, food falls directly from the "sky"; the cost of its production is less, therefore, the need for feed is less. In nature, you are unlikely to find an obese fish, and in aquarium conditions this is common. In oily fish, the lifespan is significantly reduced, and breeding can be forgotten altogether. If your pets are fat, they can safely make a fasting day, just don’t feed them once a week. This day can be combined with the day of cleaning the aquarium. After cleaning a little, but the conditions change, and the fish gets used to them, therefore, at this time she does not have to eat.
High temperatures accelerate the metabolic rate, and the need for the amount of feed increases. It should be noted that well-fed fish consumes more oxygen.
Not eaten remnants of food should be removed from the aquarium, as they may cause water damage or premature clogging of the filter. In addition, extra oxygen is consumed on decaying food debris.