JBL Cocos Cava coconut halves for aquariums and terrariums

Place it with the opening facing down, directly on the floor of the tank, without pushing it into the sand or gravel. The edge should rest on the grow medium with the notch left clear, because this single entrance reassures the animal, which has only one direction to watch. If you push it in, water no longer flows underneath and waste builds up there; placed upside down, it becomes nothing more than an open dish.

Rinse it thoroughly in clean water before first putting it in the water, paying particular attention to the sanded inside. A pass of about 10 minutes in boiling water completes this rinse: it removes any fibres left clinging and waterlogs the shell more quickly, so that it sinks rather than floats in the first few days. Over the following weeks, a light film of biofilm settles on the submerged surface, as on any plant material introduced into a tank, and you need do nothing, since shrimp and bottom-dwelling fish eat it.

A shrimp that has just moulted keeps a soft shell for a few hours, which makes it vulnerable to the other occupants of the tank. It therefore spends this time motionless and hidden, as far as possible from any traffic. Place the shell in a quiet corner of your tank: the shrimp will find the shelter it is looking for there, and the biofilm that builds up on the fibre gives it something to graze on right there. For the rest of their diet, an insect-based food suits the same tanks.

Small bottom-dwelling fish take to it for the same reasons. Dwarf cichlids that spawn under cover, such as Apistogramma, use it as a spawning site, and the female then guards her eggs behind the single entrance. If you keep a community tank, provide one shell per pair or per territorial fish, and break the line of sight between two shells with a root or a slate plate, so that each occupant keeps its own territory.