Fishmen
An interesting concept, though I think you've got too many Rares and the army itself just seems like normal humans but with a fishy aftertaste. Try to make them more unique and flavorful. And if you're going to emulate any particular race, go with Lizardmen, as they seem the closest fluffwise and ruleswise to how I'd envision Fishmen.
Basic fishmen could be S2 T2 but come in large numbers and have scaly skin. Then you add in big beasties (I like giant crabs and jellyfish, though a kraken or octopus would be hard to do) and various other hybrids. The less "human" they are, the better I==M==HO.