Aldrovandia phalacra, the Hawaiian halosaurid, is a species of ray-finned fish in the family Halosauridae.

Aldrovandia phalacra is a long, slim, cylindrical fish growing to a length of 40 to 50 centimetres (16 to 20 in).

Mature males with ripe gonads have their nostrils extended into a dark coloured tube.

The head is steely blue, darker below, with a dark line edging the gill covers.

[2] Aldrovandia phalacra is a deep water fish, living at depths of 500 to 2,300 metres (1,600 to 7,500 ft).