Fish Nutrition Calculator

Determine how much to feed your aquarium fish. Prevent overfeeding and maintain tank health with our fish food calculator.

Calculate feeding amounts for aquarium fish.

About This Calculator

Keep your aquarium thriving with the Fish Nutrition Calculator. Unlike mammals that can survive days without food, aquarium fish have unique feeding needs that require consistent attention. Overfeeding is paradoxically the leading cause of aquarium problems—causing poor water quality, algae blooms, and fish illness.

Fish don't have stomachs like mammals; their digestive tracts process food quickly and continuously. This means multiple small feedings are often better than one large meal. The "2-minute rule" is the gold standard: feed only what your fish can completely consume in about 2 minutes (5 minutes for slower species like goldfish).

Different fish species have vastly different dietary needs. Herbivores like plecos need algae wafers, carnivores like bettas need protein-rich foods, and omnivores like guppies eat a varied diet. Understanding your specific fish's needs prevents malnutrition and related health problems.

The 2-Minute Feeding Rule

Standard Fish: Feed what's consumed in 2 minutes

Slow Eaters (Goldfish, Discus): 5-minute rule

Bottom Feeders: Feed after lights out

Fish Feeding Reference Chart

Fish Type	Diet Type	Amount	Frequency
Betta	Carnivore	2-3 pellets	1-2x daily
Goldfish	Omnivore	Eye-sized portion	2-3x daily
Tetra/Guppy	Omnivore	Small pinch	1-2x daily
Cichlid	Omnivore/Carnivore	2-min consumption	1-2x daily
Discus	Carnivore	5-10 min consumption	2-3x daily
Catfish/Pleco	Omnivore/Herbivore	1 wafer per 3 fish	1x daily (evening)
Shrimp	Omnivore	Tiny portion	Every 2-3 days

Practical Example

For a 20-gallon community tank with 6 tetras and 2 corydoras: Feed a small pinch of flake food in the morning (tetras finish in 2 minutes). Add one sinking wafer in the evening for the corydoras. Skip feeding one day per week to aid digestion.

Warning Signs of Overfeeding

Cloudy or murky water despite regular water changes
Visible food accumulating on substrate or in filter
Algae blooms (excess nutrients feed algae growth)
Fish with bloated bellies or trailing feces
Elevated ammonia or nitrite levels

Fish Feeding Tips

Use a feeding ring to contain floating food and prevent waste
Fast your fish one day per week to aid digestion
Soak freeze-dried foods before feeding to prevent swim bladder issues
Rotate between 2-3 food types for complete nutrition

Scenario Comparison: Feeding by Fish Type

Fish Type	Diet	Amount	Frequency
Betta (single)	Carnivore	2-3 pellets	1-2x daily, 1 fast day/week
Goldfish (6 inch)	Omnivore	Eye-sized portion	2-3x daily, small amounts
Neon Tetras (school of 10)	Omnivore	Small pinch flakes	1-2x daily
Pleco (8 inch)	Herbivore	1 algae wafer	Every 1-2 days (evening)

Common Fish Feeding Mistakes to Avoid

Overfeeding: #1 cause of fish death. Uneaten food rots, spikes ammonia, and kills fish. Only feed what's consumed in 2 minutes.
Feeding only flakes: Flakes lose nutrients quickly. Supplement with frozen bloodworms, brine shrimp, or fresh vegetables weekly.
Ignoring nocturnal feeders: Catfish, plecos, and loaches are nocturnal. Feed sinking wafers after lights out or they'll starve.
Same food every day: Fish need variety for complete nutrition. Rotate between 2-3 different food types throughout the week.

Aquarium Fish Nutrition Benchmarks

Parameter	Tropical Fish	Goldfish	Betta
Protein content	35-45%	28-35%	40-50%
Fat content	5-8%	3-6%	8-10%
Feeding frequency	1-2x daily	2-3x daily	1-2x daily
Fast day needed	Optional	Yes (1x/week)	Yes (1x/week)

When to Use This Calculator vs Others

This calculator: Best for determining feeding amounts and schedules for freshwater and tropical aquarium fish.
Reptile Nutrition Calculator: Use for cold-blooded pets like bearded dragons and turtles (different feeding schedules).
Bird Nutrition Calculator: Use for pet birds—different dietary requirements entirely.
Pet Meal Calculator: Use for dogs and cats—mammals with calorie-based nutrition needs.

Related tools: Reptile Nutrition Calculator for cold-blooded friends, Bird Nutrition Calculator for feathered pets, and Pet Meal Calculator for dogs and cats.

Frequently Asked Questions

How much should I feed aquarium fish?

2-minute rule: only what fish consume in 2 minutes. Feed 1-2x daily. Overfeeding is #1 cause of tank problems (cloudy water, algae, ammonia spikes).

How often should I feed my fish?

Most tropical fish: 1-2x daily. Goldfish: 2-3 small feedings. Bettas: 2-3 pellets 1-2x daily. Skip one day weekly to aid digestion.

What are signs of overfeeding fish?

Cloudy water, visible uneaten food, algae blooms, bloated fish, high ammonia/nitrite. Reduce feeding and increase water changes if you see these signs.