The black diving beetle is by far the UK's most common water beetle species. It can be found in almost all freshwater habitats including rivers, ponds, lakes, ditches and even temporary puddles. Unlike the much larger great diving beetle (Dytiscus marginalis), the black diving beetle only reaches about 1cm and is safe to keep with small fish (large or predatory fish will try and eat it).
Though it is still a predator and will eat small invertabrates and can be fed bloodworm, daphnia and small insects, it will also scavange and will sometimes eat fish flake or pellet food. If being kept in an indoor aquarium, a secure lid is impotant as the beetle is able to climb.
Black diving beetle (Agabus bipustulatus)
The Great diving beetle will breed in ponds provided there are both male (males have smooth wing cases) and female beetles (females have grooved wing cases) and the pond has food and some aquatic plants for them to lay their eggs. The larvae, like the adults, are voracious predators and will hunt a wide range of prey like other insects, tadpoles and small fish. They breath through a tube on their abdomen and therefore need to stay close to the surface. When they are ready to change into adult beetles they will leave the water and burrow into mud near the pond where they will pupate before returning to the water. While the great diving beetle can fly, it rarely does so if there is enough food for it.