Hi all, I'm very new to fish-keeping and I'm just a bit concerned about how to look after my fish in the best way possible. It's probably worth noting that I happened to find this 20 litre tank in a house I was working in. I was there to carry out general maintenance work and some idiot forgot about their fish. There was one blue/black Siamese fighting fish and 4 neon tetras in the same tank. It was quite dirty and looked in a bad way. I took it all home with me as nobody was going to claim them if I didn't. Since bringing them home, one of the tetras has died, but the other fish are still OK. I've added a stone Buddha ornament, 2 plants (one tall and one short - I know the Betta has the labyrinth organ and needs to be near the surface so the tall plant helps with this) and have the submersible heater and filter. I've got the thermometer in too so I can keep an eye on the temperature at all times. I bought two albino corydoras - which I LOVE - but one has died after about a week. Pretty sure it had swimbladder as was suggested by the people at Pets at Home. My ammonia level was too high so I've sorted that out today. It's been quite stressful because I obviously want them all to be healthy and enjoy life but I didn't know how hard it would all be. I'm definitely wanting to keep all the fish and maybe even get a bigger tank in the future, but I want to make sure I'm doing it right now. I'm just wondering, in my 20 ltr tank, with two plants, one buddha, one betta, 3 neon tetras and now one cory, is there anything else I need? And I can I add another cory (after I'm 100% sure my ammonia levels are better and I make sure it's in good condition) or should I look for another kind of bottomfeeder? The two corys loved being together and they're wonderful fish to have. Just dont want my one remaining cory to be depressed or whatever from being alone. Any help at all would be awesome. And would a snail be a good idea to add? Maybe a shrimp? I don't want to add too much as it's a small tank. Cheers guys if anyone can help.