Fish diets are easy and totally predictable. As as aquarium owner, you shouldn't be too concerned about providing a wide variety of foods. However, you should be watchful about the amount the fish is receiving. Overfeeding fish is far more serious than giving it a variety of foods to choose from each day. As long as the foods you feed your fish each day meet all the requirements of a growing fish, you need not overly concern yourself about providing variety. Though fish do appreciate and need some variety, most commercial fish food provides proper nutrition for your fish.

A fish needs a balanced diet of proteins, carbohydrates (though very few), fats and oils, and minerals and vitamins. Proteins are the foundation of a fish's diet and the most important element to facilitate growth and body tissue replacement. Carbohydrates provide energy, as do fats and oils. Meats are a good source of carbohydrates, fats and oils. Vitamins are live organic compounds that discourage disease and facilitate body functions. Vitamin A, for example, is in the plants your fish feed on and will help develop and intensify your fish's color. Green plants are vital to a fish diet, and often aquarists underestimate the importance of large amounts of greens for their fish.

Provide a daily diet of fish flakes, greens and occasional meat-based foods (if your fish is carnivorous) and your fish will do great.