Are you going to only take pictures of your fish? What type of camera do you like? A point and shoot or something with more manual options. Are you going to print? How large are you going to print? There's plenty of camera below $1k, so i guess more information will be needed to make a good recommendation.
Some photos arent well taken(dark faces againest a bright background), but thats my fault, not the Camera's. A little changing of the metering modes will solve it. I didnt do it at that time. All photos taken in auto mode with no changes.