They get decent growth for all stats, even their weakest gets 1. Their magic growth in particularly is quite good. However, they don't get many skills to make use of it, with both of their fixed skills not reliant on stats at all. One of them is unique to Angler Fish, BlindingLight, which Blinds all surrounding units.
They have Glowing, which removes Vision penalties, allows access to shadow biomes, and reveals full enemy party compositions.
The easiest way to get one is by using a Siren and a Lymean, so try and get some of the Siren's better skills on your Angler Fish, since they have similar stats to use those skills with. See the Siren page for skill combinations and roles your Angler Fish can take over.
Angler Fish have a beauty of 100, meaning that brothel work is very lucrative for them.