If you are after a P&S only, then I would look at some used or older Canon models. Being a Nikon shooter, with DSLRs and P & Ss in the past, I can tell you that I have found Canon models to be far superior. I personally like the Powershot SD--- IS series for general photography, and even on the cloudy setting you can get some decent colors out of your reef tank photos. Your general answer here will be similar to above, save up and get a low end DSLR or the Canon G10, and I would agree with them. But, if $200 is the max you can spend then you have my opinion, you could look at one of those Canon models in the 6 - 8 megapixel range.