Overview
Overfeeding is the single most common cause of algae and nutrient problems in new reef tanks. The guiding principle is simple: feed the fish, not the tank. This guide covers how much, how often, and how to feed corals without fouling your water.
How Much to Feed
A good rule of thumb is to offer only what your fish can completely eat in about one to two minutes, with no food drifting uneaten into the rocks or sand. Feed small portions and watch — it is always better to feed a little and add more than to dump in a big pinch that decays. Adjust the amount to your actual stocking, not the size of the tank.
How Often to Feed
Most reef fish do well on one to two small feedings per day. Grazers and planktivores like tangs and anthias graze constantly and appreciate more frequent, smaller feedings, while large predators eat less often. On a nano tank especially, err toward less — the small water volume punishes overfeeding quickly.
Feeding Corals
Photosynthetic corals get most of their energy from light and need little or no feeding, but LPS, non-photosynthetic corals, and many others grow faster when fed. Target-feed them small meaty foods with the return pump briefly off so the food stays put, a couple of times a week. See our species guides for which corals actually want feeding.
Variety and Quality
Rotate a mix of quality frozen foods, dry pellets or flakes, and marine algae (nori) for herbivores, and soak foods in a nutritional additive for an extra boost. Variety covers nutritional gaps and keeps fish interested.
Signs You Are Overfeeding
Climbing nitrate and phosphate, nuisance algae, detritus piling in low-flow areas, and a cloudy or smelly tank all point to overfeeding. The fix is to scale back portions, improve flow and export, and be patient — nutrients take time to come back down.
Related Guides
- Getting Difficult Fish to Eat
- Food Additives: Selcon, Garlic & Vitamin C
- Lowering Nitrates & Phosphates
Frequently Asked Questions
How much should I feed my fish?
Only what they can eat completely in one to two minutes, with nothing drifting away uneaten. Feed small amounts and add more if needed rather than dumping in a large portion that decays and pollutes the water.
Am I overfeeding my tank?
Likely yes if you see rising nitrate and phosphate, nuisance algae, or detritus building up in low-flow spots. Cut back portion sizes, improve flow and nutrient export, and give the tank time to recover.
Should I feed my corals?
Photosynthetic corals mostly feed on light and need little, but LPS and non-photosynthetic corals grow faster with target feeding a couple of times a week. Feed small meaty foods with the pumps briefly off.