Species description

Care, breeding and tankmates

Fish profile

Temperament

Territorial

The Crazy fish gets its name from its peculiar, slow-moving, upside-down stealth behavior. They are incredibly patient ambush predators that remain motionless for hours waiting for prey to pass. While deadly to small fish, they are otherwise peaceful and completely ignore tank mates that are too large to eat.

Diet

Carnivore

They are strict carnivores that almost exclusively eat live foods in the wild, such as small fish, shrimp, and insects. In captivity, they can often be weaned onto frozen meaty foods like bloodworms, krill, and pieces of fish or shrimp. Providing a varied, high-protein diet is essential for their long-term health and coloration.

Sex ratio

Solitary

There are no clear external differences between males and females. They are best kept singly or in pairs, as males can be territorial toward one another in smaller tanks. If kept in a group, a large aquarium with numerous visual barriers is necessary.

Feeding frequency

Once daily

Being ambush predators that swallow relatively large meals, they do not need to be fed every day. Feeding them a substantial meal every other day or three times a week is usually sufficient. Careful observation is required to ensure they are getting food, as they wait for it to come to them rather than actively chasing it.

Bioload

The Crazy fish, or Duckbill sleeper goby, produces a moderate to heavy bioload due to its predatory diet. They require high protein meals which inherently generate more nitrogenous waste. A robust filtration system and strict adherence to a regular water change schedule are imperative to keep nitrates low.

Flow

Strong

They naturally inhabit mangroves and estuaries where water flow can vary, but generally prefer areas of calmer water to set up ambushes. A moderate flow is acceptable, provided there are plenty of slow-moving areas and hiding spots. Extremely strong currents will exhaust them.

Jump risk

No

Reproduction

Oviparous

Breeding Butis butis in the home aquarium is incredibly rare and difficult to achieve. They are believed to be cave spawners where the male guards the eggs until they hatch. The fry are exceedingly small and require complex estuarine conditions and microscopic live foods to survive.

Compatibility & tankmates

Verify

They are highly predatory ambush hunters that will eat any fish or crustacean that fits into their surprisingly large mouths. They should be kept with fish of similar size or larger, such as Monos, Scats, or large rainbowfish in a brackish setup. Aggressive tank mates should be avoided as Butis butis is relatively inactive and prone to harassment.

Tank level

Bottom

They are famous for their bizarre habit of resting upside down against floating leaves or vertically against plants and hardscape. They utilize all levels of the tank depending on where they choose to ambush, but are often found near the top or middle clinging to surfaces. They rarely swim actively in the open water.