In their natural habitat no fish live exclusively on animal or plant food. Meat eaters (carnivores, such as cichlids and labyrinth fish), when eating fish, crabs, and insects, also devour the intestines of their prey, which contain green algae and other plants. Therefore, these fish need plant food as an occasional supplement to their diet. Plant eaters (herbivores, such as sucker-mouth armored catfish) may also eat baby crabs and worms that are found among the algae or on plant leaves. You can offer them worms, larvae, and dry food tablets.
Types of Plant Food
Algae grow in every aquarium but for the most part do not meet the needs of fish. All herbivorous fish or those that eat plants as a part of their diet (such as cichlids from Lakes Tanganyika and Malawi) are especially fond of dry vegetable flakes. Lettuce is often recommended as a food for herbivorous fish. It has been found, however, that fish stopped spawning if they were fed commercially grown lettuce that had been treated with chemicals. They did not resume spawning until several weeks after the lettuce was removed from their diet. Therefore, feed your fish only lettuce that has been raised organically and contains no chemicals or additives. Spinach can be used fresh (when it’s new) or thawed (after freezing). It’s a favorite food, but many fish must get accustomed to it slowly. Wild plants such as dandelions greens and chickweed can also be used to feed fish after they become accustomed to them. Surplus water plants from other aquariums, which occasionally become available when pruning and planting, can be prepared as food for plant eaters. Slugs and other animals that live on the plants are also eaten. Large cichlids enjoy duckweeds.
How to Feed
Lettuce, spinach, and wild plant greens should be soaked for a short time before feeding so that they become soft. Frozen spinach need only be thawed.
How Often and How Much to Feed
Breeding fish are not fed more often than other fish in the community aquarium. However, they receive live food, which is richer in nutrients and can thus provide them with additional vitamins and iodine. If you purchase fry that you intend to use later for breeding, do not keep them in the company of larger or more lively fish. Such fish can deprive the fry of food.