Flowerhorn Cichlid Stocking

Keeping Flowerhorn Cichlid

The Flowerhorn Cichlid grows to about 15 inches and needs a minimum of 75 gallons. Its bioload is high, meaning it produces a large amount of waste for its size, a key factor the "one inch per gallon" rule ignores. It doesn't need a large group, but plan tankmates around its temperament. Temperament is aggressive, so choose tankmates carefully or keep it in a species-only setup. Use the calculator above to see how a group fits your tank's real volume before you buy.

What size tank does a flowerhorn need?

A 75 gallon for one adult, and a 90 or 125 for a large male. A flowerhorn is a man-made hybrid of Central American cichlids, first bred in Malaysia in the 1990s, and a healthy one reaches 12 to 16 inches. The calculator counts it at about 15 inches with a high bioload, so one fish is worth 60 units of load: more than twenty neon tetras.

By waste alone, one flowerhorn in a 55 gallon reads 64%, inside the comfortable band. The 55 still fails, and not because of bioload. It is 13 inches front to back, which is shorter than the fish. A 15-inch cichlid in a 13-inch-deep tank cannot turn around without bending, and a fish that cannot turn freely is a stressed, aggressive fish. The 75 gallon has the same 48-inch length but 18 inches of depth, and that is what the minimum is really buying. One adult in a 75 reads 47%.

One per tank

Flowerhorns are kept alone. They were bred for size, color and the nuchal hump (the "kok"), and aggression came along with the package. Two adults in a 125 gallon read only 56% by bioload, and the number is meaningless: one will usually kill or cripple the other. Tankmates in general are a gamble. Some keepers run a flowerhorn with large, fast, armored fish in 150 gallons or more, but plenty of flowerhorns tolerate nothing, and you will not know which you have until it happens.

That makes the tank the fish's whole world, which is the real argument for going larger than the minimum. A single fish in a 90 or 125 gallon is calmer and easier to keep clean than the same fish in a 75.

Filtration and water changes

This is a heavy eater with heavy waste. Plan on filtration rated for a tank at least twice the size of yours, usually a large canister or a sump, and 30 to 50 percent water changes every week. The bioload guide shows why: nearly all the ammonia in a tank starts as protein in food, and a flowerhorn eats a lot of protein. Keep the water at 80 to 85 °F with a pH around 7 to 8.

Protect the equipment. Flowerhorns dig, move rocks and attack heaters, so use a heater guard or an inline heater, keep decor to a few heavy stones that sit on the glass rather than the sand, and fit a secure lid. They jump.