This is too similar to our old logo. For the colors we are after black and silver/chrome with possible blue highlights and the fish we would prefer to be more of a symbol or abstract rather than cartoonist style. Have a look at some web 2.0 logos for inspiration. But a nice start.
Could we see some different colors possibly orange or gold/silver. In Australia the majority of aquarium fish we keep are freshwater tropical fish like catfish, angel fish, sharks, gourami's and African cichlids. Because of our climate we have trouble keeping marine fish like the ones you have included. but we would love to see some examples with tropical fish and different colors.