To do a photo contest, there are always rules that usually don't make everyone happy. My experiences involved in a photography forum (APF), most of the logistics to provide a level playing field is quite difficult.
Number one, there is the DSLR vs the P&S controversy. In most cases, the DSLR photographers have the edge over the P&S folks. The main reason for that is the equipment is better suited for aquarium photography. All DSLR formats provide individual camera settings that produce better images, better lenses, remote flash capabilities, and the user is normally more technically astute in photography.
Then there is the two different philosophies about a fish photo contest. Should people's votes weigh more heavily on the aesthetic qualities of the image, or the technical proficiency of the photograph? Being a photographer, as opposed to a picture taker, I feel that technical results are more important than showing a blurred mouthbrooder spitting her fry. (This last comment provides the ammo for the ongoing debate, I'm sure).
So with that said, a photo contest can be fun, as long as it doesn't involve serious competition. I know I haven't been able to come up with a format that allows the casual entry be fairly competitive to the advanced photographer's entry. I think there is a strong advantage to the DSLR users. So, the only other choice would be to have two contests. Digital P&S and DSLR.
And having only a few entries in a contest waters the whole thing down too. Currently, we only have a handful of members that share images on this site. Most of the better photographers don't even bother. Perhaps they would rather sit on their laurels than share. Just a guess. :confused0083: