Hydra (freshwater polyp)

Care at a glance

The hydra is a tiny freshwater polyp that attaches by a foot to glass, plants or wood and waits for prey with a ring of thin tentacles. Scientifically it is famous for its regeneration: a complete new animal grows from a small fragment.

In a tank with fish it is mainly unsightly, but in a shrimp or breeding tank it is harmful: it catches newborn shrimp and fry. It almost always appears after generous feeding, so feeding less is the first step; beyond that remove them mechanically or use a treatment that spares shrimp.

Good to know

• Preys on shrimp and snails

Natural predators

• Three spot gouramiTrichopodus trichopterus
• Paradise fishMacropodus opercularis

Related species

• Spixi snail (zebra apple snail)Asolene spixi
• Redclaw crayfishCherax quadricarinatus
• Red claw crabPerisesarma bidens
• Vampire crabGeosesarma sp.
• Giant freshwater shrimpMacrobrachium rosenbergii
• Japanese trapdoor snailViviparus malleatus