Leoparden-Drückerfisch (Balistoides conspicillum)

Don't squeeze a trigger fish!

A very special family of fish lives in the aquariums of the German Oceanographic Museum: the Triggerfish (Balistidae). They are very striking fish: they have a high, oval body shape, an unusual colour and a very distinctive head shape.

Triggerfish are very charismatic. The aquarists at the MEERESMUSEUM (OCEANOGRAPHIC MUSEUM) experience time and again the way that these animals can be very curious, sometimes affectionate, but also at times aggressive. Triggerfish like to hide away ("verdrücken" in German, like their German name "Drückerfische") and sometimes they do this in caves and crevices. However, their German name comes from an incorrect translation of the English "triggerfish". The English name refers to the first dorsal fin. The first dorsal fin is formed in the shape of a strong spine; if it is raised, the second, smaller dorsal fin ray can fold forward, so that the first dorsal fin is held in place. This safety mechanism acts mechanically like the safety on the trigger of a rifle, giving the fish its name in English.

The safety mechanism found in triggerfish also often poses problems for aquarists: if a fish needs to be moved to another tank, the water in the tank has to be drained, in order to catch the fish. Often the triggerfish have withdrawn so far into the decoration in the tank, that the keepers have had to pull the animals out of their hiding places. And unfortunately, triggerfish also sometimes like to bite very much! The divers at the OZEANEUM also know this well. Over there a Grey triggerfish (Balistes capriscus) is making its rounds of the large schooling fish tank. The divers have to beware of its bite!

But the Grey triggerfish also has its gentle side. It lived for a while in quarantine behind the scenes and there it formed a very unusual friendship: it shared a tank there with a Dusky grouper (Epinephelus marginatus). The two of them always swam together and the keepers considered them to be inseparable. When the grouper had to relocate for a few weeks to a different tank, the shy triggerfish changed its behaviour and felt uncomfortable: it ate less and mostly remained in a corner of the tank.

The separation did not, however, last long and both fish could soon move together to the large Atlantic Tank. There they go their own ways now, but occasionally you can find them both together on the whale skeleton.