Feeding reef fish well is about more than “once a day.” It is a plan that matches species needs, tank size, and filtration. With a few basics, you can boost color, growth, and disease resistance.
Start with fish needs and a simple schedule
Different reef fish eat in different ways. Tangs and rabbitfish graze all day. Wrasses and anthias hunt small meals often. Clownfish and gobies do well with fewer feedings. Match your schedule to that natural pattern.
Use a baseline plan for mixed reefs. Feed 2 small meals per day for most community tanks. Add a third micro-feeding for active planktivores. Keep each feeding to 30–60 seconds of visible eating. Remove uneaten food after 3 minutes.
Portion size should fit your filtration. For a 40–75 gallon reef, start with 1/8 to 1/4 teaspoon of small pellets per feeding. For frozen, start with a cube per 50–75 gallons. Thaw and strain frozen foods first. This reduces phosphate spikes.
- Herbivores: Nori sheet 5×5 inches, 1–2 times daily.
- Omnivores: Pellets in the morning, frozen in the evening.
- Planktivores: 3–5 tiny feedings, or an auto-feeder plus frozen.
If you need help choosing foods, see our reef fish diet guide. For new tanks, review cycling a saltwater aquarium first. Feeding is easier with stable biology.
Choose foods that cover nutrition and keep water clean
Use at least three food types each week. Combine a quality pellet, a frozen mix, and a seaweed option. Pellets give consistency and vitamins. Frozen foods add moisture and variety. Seaweed supports gut health for grazers.
Pick the right particle size for the fish mouth. Nano fish often need 0.5–1.0 mm pellets. Medium community fish handle 1–2 mm. Large angels and triggers may need 3–5 mm. Too-large food gets spit out and rots.
Soak dry foods when needed. Use tank water for 2–3 minutes before feeding. This helps timid fish accept pellets. It also reduces floating pellets that go into the overflow. Avoid oily “enhancer” soaks every day. Use them 1–2 times weekly.
Watch nutrients with a test kit and a routine. Aim for nitrate 2–20 ppm in most reefs. Keep phosphate around 0.03–0.10 ppm. If nitrate hits 30+ ppm, reduce portions by 20% for a week. If phosphate rises above 0.15 ppm, strain frozen food and clean the filter socks sooner.
- Thaw frozen food in a cup, then pour through a fine mesh net.
- Feed with pumps on, then pause flow for 5 minutes if needed.
- Use a feeding ring to keep food from going straight to the overflow.
Troubleshooting: common feeding mistakes and quick fixes
Overfeeding is the top problem. Cloudy water, film algae, and rising phosphate are common signs. Cut feeding volume by 25% and keep frequency the same. Clean the skimmer cup and neck. Replace or rinse mechanical media every 2–3 days.
Underfeeding can look like aggression and weight loss. Watch belly shape and behavior. A pinched belly means the fish needs more calories. Increase feeding by one small meal daily. Add higher-energy foods like mysis or enriched brine. Keep portions small to protect water quality.
New fish often refuse food in the first 48 hours. Offer several options in tiny amounts. Try frozen mysis, then small pellets, then a sheet of nori. Dim the lights for the first feeding. Use a feeding station near cover. Quarantine helps you train fish to prepared foods. See our reef fish quarantine protocol for a simple setup.
Some foods can trigger messy waste. Large chunks of seafood can spike nutrients fast. Use finely chopped pieces under 5 mm for most fish. Rinse raw seafood to remove packing juices. If you run an auto-feeder, start at 1–2 rotations twice daily. Check nitrate and phosphate after seven days.
- If fish fight at feeding: spread food across the tank, not one spot.
- If corals look irritated: reduce broadcast feeding and target feed instead.
- If nitrates climb: keep feeding steady and increase export slowly.
Good feeding is repeatable and measured. Keep notes for one week and adjust one variable at a time. Your fish will eat better with stable parameters and calm routines.
Sources: Fenner, R. (2001) The Conscientious Marine Aquarist; Borneman, E. (2001) Aquarium Corals; Sprung, J. (2005) The Reef Aquarium (Vol. 3).
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