3a Tropical American river-fish of family Cichlidae (10) A _ G _ L _ H _ R _
(The only close candidate I can find is "Angel shark" which must be wrong!)
I agree, it is wrong. Chambers 10th gives angelshark as alternative name for the shark definition of angelfish.
It then goes on to give another definition(of angelfish) which is as the clue has it.
Many thanks to everyone - I intend to submit the puzzle with Angel Shark and some subtle comments as to the possible inaccuracy of the questions. (I doubt if anyone will reply - any bets!?)