Mono

Mono Tank Setup

A tank of at least 450 litres (119 US gallons) works well. Keep the water at 75-82°F with a pH around 7.5-8.5, and set up both cover and open swimming space where they spend most of their time (Mid). Always keep a group of at least 6 of their own kind - kept alone or in pairs they tend to turn shy, nippy, or wash out in colour. They grow to around 25 cm, so plan the tank size and filtration for a full-grown adult rather than the small juvenile you see in the shop.

What Do Monos Eat?

They're not fussy eaters - feed a varied diet, rotating good-quality dry, frozen, and gel foods rather than the same thing every day, and match the food size to their mouths.

Mono Tank Mates

Brackish-to-marine shoaling fish: juveniles may be sold in fresh water, but adults need strongly brackish to full marine water - kept fresh long-term they suffer chronic skin and fin disease. Keep a group of 6+ (pairs and small groups fight) in a tall tank of at least 450 litres, as adults reach 20-25 cm and are very deep-bodied. Fast, nervous swimmer that may eat very small fish and fry; not a freshwater community fish. The Mono is semi-aggressive, which is the first thing to weigh up when you choose tank mates. At around 25 cm fully grown, it needs tank mates that can hold their own against its size and appetite. It's a shoaling fish, so settle a group of 6 or more of its own kind before adding anything else - a stressed, lonely fish is far more likely to nip or hide. Before you buy, run your full stocking list through our stocking calculator. It weighs temperament, adult size, and water needs together, which a single species page can't do on its own.

Are Monos Good for Beginners?

Not a sensible first purchase. Get the tank cycled, keep easier fish stable for a year, then revisit if you still want the extra work this species demands.