Fish Food and Feeding
Fish primarily have high protein diets. Even fish that graze on algae receive protein from the bacteria and small microbes they ingest with the algae. When selecting food for your fish a food high in protein will be the best for conditioning, breeding, and growth.
Frozen, fresh, and live foods will have the highest protein content. Frozen food comes in many varieties for fish fry to large cichlids, pacus, and arowanas. For larger fish the fish market is a good place to find food like fresh fish and shrimp. Nori seaweed that is used for making sushi rolls is an excellent food for fish that like algae in their diet.
Protein content in dry flake and pelleted foods is highly variable. Dry food can have fish or krill as a primary ingredient. Krill based foods have natural color enhancer, and fish fed on this type of food will often have more vibrant color than fish fed fish based dry foods. Dry foods use wheat or rice as a filler and thus have lower protein content than most fresh and frozen foods.
When feeding your fish, a general rule that is often used, is not feed any more than they can consume in five minutes. This does not hold true in all cases. Discus are slow eaters and it may take them 15 minutes to fill up. You should also make sure enough food drifts down to the bottom for any bottom feed loaches and catfish.
If you are changing the type of food you are feeding your fish you should feed them the new food only in small quantities, as it often takes a week or longer for fish to become accustomed to the new food.