As I had just PMd Hans about, the exhibits at the NEAq (where I am a volunteer at the Freshwater Gallery) are a lot bigger than they appear. The Red-tailed cat is 18 yrs old, he dosen't move much even when provided lots of clear swimming space. You can only see 1/3 of the rheotaxis (rummynosed) tank from the front. Not only that, but daily water changes are performed and the fish are treated as soon as they are noticably ill. Most of the fish there are over 5-6 years old due to such attentive care. Thanks,
Ryan
P.S. The "20 long" tank you talked about is about 300 gallons, you can only see 120 of it.