What to Feed Your Fish: A Comprehensive Guide

It seems for every type of fish there is a fish food, goldfish food, cichlid food, sinking pellets, catfish pellets, algae wafers, and that’s before you get to the various types of frozen food, live foods and supplements.

So what do we need to feed our fish?

Replicating a Natural Diet for Healthy Fish

Many of the fish we keep as pets originate from diverse environments such as the Amazon rainforest, where they evolved to thrive in very specific niches. This includes precise water conditions, temperatures, and available food sources. Although fish like goldfish and koi have been bred in captivity for many generations, others are closer to their wild ancestors and still benefit from diets reflecting their natural food intake.

In the wild, fish diets vary and include vegetation, fruits and vegetables that fall into the water, algae growing on rocks, insect larvae, and smaller fish. While it is challenging to provide all these elements in captivity — especially in mixed community tanks—aiming to replicate these natural food types helps keep your fish healthier and more active.

Understanding Macro and Micronutrients in Fish Diets

Fish nutritional needs include macronutrients such as protein, carbohydrates, fats, and fibre, alongside micronutrients like vitamins and minerals. Protein is vital for growth, tissue repair, and immune function. Depending on the species, fish may require from 35% up to 55% protein in their diet with carnivorous species needing higher amounts and herbivores less.

Good commercial fish foods are formulated to provide a balanced intake of these nutrients. However, cheaper brands often contain fillers that can degrade water quality and reduce fish health, so opting for reputable, higher-quality brands is advisable.

Basic Diets: Commercial, Homemade, and Live Foods

Professional breeders often supplement their fish's diet with fresh or homemade foods tailored to species-specific needs. For hobbyists, a combination of commercial foods and live cultures can be very effective.

Live foods such as brine shrimp, daphnia, glass worms, vinegar eels, and micro worms provide fresh protein and enrichment. These can be cultured at home with starter kits, ensuring a sustainable live food source. Larger live foods like earthworms are suitable for bigger fish, while even garden-collected snails (from pesticide-free areas) can be a special treat for species like loaches.

Feeding Specialized Ingredients: Hearts and Fish

Some breeders, particularly of species like discus, feed beef, pork, or turkey hearts mixed with vegetables and vitamins. Although these hearts are not natural in wild diets, the macronutrient composition can closely imitate the nutritional profile of their natural prey.

Feeding fish to fish involves risks such as disease or parasites transmission; therefore, live feeder fish are generally discouraged. Commercially prepared frozen fish is safer due to parasite clearance by freezing and is more ethical in terms of animal welfare.

Vegetables: Vital Fibre and Variety

Many aquarium fish require a substantial amount of plant matter in their diet. Vegetables like peas (shelled to prevent choking), sliced and blanched courgette (zucchini), mushrooms, melon, carrots, and leafy greens can be offered. These should always be thoroughly washed and ideally organic. Weighing down these foods helps bottom-feeders access them easily. Garlic cloves floated in the tank are believed to help reduce nitrates and act as a natural antiseptic.

Target Feeding to Support All Fish

Some fish species compete aggressively for food, potentially leaving bottom-dwellers or shy fish underfed. Using a turkey baster or feeding tongs to deliver food directly to less competitive fish a few times a week ensures they receive sufficient nutrition.

General feeding guidelines recommend offering only the amount of food your fish can consume within three minutes and promptly removing uneaten food to maintain water quality. Nocturnal species may require feeding after lights out, which is acceptable in a well-filtered healthy tank.

Common Mistakes to Avoid When Feeding Aquarium Fish

Overfeeding is the most frequent error leading to poor water quality and fish health problems. Using a variety of foods appropriate to your fish’s species, avoiding low-quality fillers, and maintaining consistent, moderate feeding portions helps prevent these issues.

Also, not tailoring feed types — such as not providing sinking pellets to bottom feeders or inappropriate flakes to delicate species — can cause malnutrition or stress. Culturing live foods promotes variety and improves fish vitality.

Summary and Next Steps

Feeding your fish a balanced diet that mimics their natural food as closely as possible promotes health and longevity. Incorporate a mix of high-quality commercial foods, live or frozen treats, and fresh vegetables. Tailor feeding routines, invest time in target feeding where needed, and always be mindful of avoiding overfeeding.

By carefully choosing your fish foods and feeding approach, you provide your aquatic pets with a nourishing and enriching diet that supports vibrant behaviour and well-being.