if ur planning on getting rid of all ur current filtration, u might have to spend a little more then u would like ($150). however, u can always try to find what ur looking for on craigslist or in the classified. a 90 with a single Oscar wont be too bad, anymore Oscars or fish that produce that type of mess would require way more then ur set budget would allow. keep this in mind if u plan on getting more O or other messy eaters. the Eheim pro series or a FX 5 or Fluval 405 would be ur best bet IMO. another option would be to buy two small canister filters; i would recommend 2 Eheim 2213 or 2215, again depending on how much u wanna spend.
