Fish Feeding Calculator

Comprehensive Guide: Fish Nutrition, Metabolism & Feeding Portions

Overfeeding is the leading cause of poor water quality, fish disease, and premature mortality in home aquariums. In nature, fish are opportunistic foragers adapted to intermittent feeding; in captivity, food is abundant and over-consumption leads to fatty liver disease, swim bladder impaction, and severe ammonia spikes.

1. Nutritional Demands by Species Diet

Different fish families require distinct macronutrient ratios:

• Carnivores (Bettas, Oscars, Discus, Pufferfish): Require high protein (45%–55%) from insect, crustacean, and aquatic animal sources, moderate fat (6%–10%), and minimal carbohydrates (<15%).
• Omnivores (Tetras, Guppies, Barbs, Angelfish): Require balanced nutrition with 35%–42% protein, incorporating both marine proteins and spirulina/plant matter.
• Herbivores (Plecostomus, Otocinclus, Mbuna Cichlids): Require high-fiber, low-protein diets (25%–32% protein) rich in algae, kelp, zucchini, and spirulina to prevent fatal digestive bloat ("Malawi Bloat").

2. The Mechanics of Daily Feeding Portions

As poikilothermic (cold-blooded) animals, fish do not expend energy maintaining a constant internal body temperature. Their metabolic energy requirement is roughly 10% that of mammals of equivalent weight:

• Adult Community Fish: Require approximately 1.5% to 2.5% of their body weight in dry food daily, split across 1 or 2 small feedings.
• Juvenile & Growing Fry: Possess small stomachs and rapid metabolisms requiring 5% to 8% body weight daily, split across 3 to 5 micro-feedings.
• The Golden Rule: Feed only what your fish actively consume within 90 to 120 seconds. Any food sinking uneaten to the bottom decays into ammonia and fuels bacterial blooms.

3. Food Form Variety & Storage

Relying on a single dry flake leads to nutritional deficiencies. Rotate between:

1. High-Grade Micro-Pellets: Retain vitamins better than thin flakes and do not dissolve as quickly.
2. Frozen / Live Foods: Bloodworms, daphnia, brine shrimp, and mysis shrimp provide essential moisture, roughage, and digestive enzymes.
3. Weekly Fasting: Fasting healthy adult fish for one day per week clears the gastrointestinal tract and prevents swim bladder constipation.

Monitor and adjust your feeding rates using the Fish Stocking Calculator and Water Change Scheduler. Consult the FAO Aquaculture Nutrition Guidelines and PetMD Fish Diet Advice. Find more tools in our Fish & Aquarium Category.