I would definitely find a local fish store and forget Wal-mart. Wal-mart is like the fish grave yard. Find a local store and try not to go to a chain store. Now as for fish. If I were you I wouldn't get a fish that gets more than 1 1/2- 2 inches in length. There fore if your going to go Tetra don't get Congos, Diamonds, or Red Eyes. White Clouds, Bleeding Heart, Neon, Head and Taillight, or Lemon. You may also want to look into Livebearers and small Danios. A few other Tetras that you should stear clear of are Emperors, Rummynose, and Cardinal. The reason Cardinals are on my list is because they like warmer temps as well as soft acidic water. As for a catfish you should pick up 2 green Corydoras or Panda Corydoras and for the pleco get something like a Clown Pleco or Zebra. These two plecos ore dwarf Plecos and they stay rather small. If the algae doesn't get real bad just pick up a few Otociclus. That's all I can think to tell you rite now. If you have any other ?'s put them up. Also run a Google search on any fish that I posted about to get info on individual species.