Crazy fish

Care at a glance

Overview

Butis butis is an ambush predator, best kept on its own or only with fish far too big to be eaten. It lurks under wood and among roots, then lunges at passing prey, and it will take any fish or shrimp that fits in its mouth, so tankmates need choosing with real care. Despite the aggressive feeding it ignores anything too large to swallow and is not a general bully. Feed meaty foods: earthworms, prawn pieces, and frozen items, and wean it onto larger sinking foods over time. Give it around 250 liters with plenty of shade and cover; it often settles best in lightly brackish water, though juveniles are sold and kept as freshwater fish.

In the wild

The crazy fish ranges widely through Indo-Pacific coastal waters, from estuaries and mangroves to the fresh lower reaches of rivers, where it hangs motionless among roots and snags waiting to ambush prey. Furnish its tank with bogwood, rockwork, and robust plants for shade over a soft bottom. It likes warm, hard, alkaline water, about 24 to 28 C and roughly pH 7.0 to 8.2, and long term it does best with a little marine salt added.

Good to know

Butis butis belongs to the sleeper goby family Eleotridae and reaches about 15 centimeters. It is called crazy fish for its habit of hanging and hunting at odd angles, often head down or even belly up beneath cover, which is unusual balance control for a fish. It is a predator of small fish and crustaceans, and its aquarium breeding is not recorded, so it is kept as a single oddball rather than bred.

Did you know

The crazy in its name is about orientation, not temper. Butis butis will happily rest and even stalk prey upside down or vertically under a log, treating which way is up as an optional detail.

Common questions

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