Solid looking raised bumps are evident on the skin.
Cercariae which develop as a 2nd stage of digenetic trematodes. Transmitted by an intermediate host, usually snails. This is also the cause of 'Black Spot' disease.
Fatal is left untreated. Quarantining procedures can help to reduce infection. Keep tank or pond clear of all snails, so the life-cycle will be stopped.
Parasite identification, succession and infection pathways in
perch fry (Perca fluviatilis): new insights through a
combined morphological and genetic approach
Jan 2013 by JASMINCA BEHRMANN)