New fish tank... need help

Question
Alright.. a long story, so I'll try to keep it short...

My next-door neighbor decided to move out, but he can't take his 55-gallon freshwater tank with him. His friend, who he was going to give it to, suddenly couldn't take it. So my neighbor thought of me, since I like aquariums and want to be an Ichythologist. I said I'd be happy to take it... oh, if I'd only known what I was asking for.

Yesterday I went to his house to unload the aquarium and transfer it to my house piece by piece. The thing was overrun by plants and the water was an eerie green color, soon to be turned brown by the crap at the bottom. My brother and I took most of those plants out (almost all of which I'm not going to keep; there was an entire trashbag full of them!) then tried to locate whatever fish might be alive in there. Turns out there were about ten guppies and what look like fry (probably from the guppies?), a Fantail Goldfish, a betta, a couple platys, and something I'm absolutely unfamiliar with. I'm not necessarily sure yet, though, what all the fish are since the water was so murky/muddy when we got them, but I can recognize some of the species. And I know that not all of them are compatible.

The gravel bed (mud-bed might be a better term) was even worse, if such a thing is possible. There was an inch-and-a-half of fish waste and gunk sitting on top, and below was very muddy, slimy, disgusting 'gravel.' The filter likely hasn't been run since the eighties.

So, in conclusion, my neighbor is the worst aquarium-keeper to have ever existed and now I have a grimy disgusting tank and I'm not sure what to do with it. I'm thinking I should throw away all the gravel and get a new filter and aeration system and decorations and clean the thing spotless. I'll likely need to replace all the water too, so I'll have to treat the fish like I'm introducing them to an all-new environment, and float them in bags and slowly add new water over a long period of time... The fish are in large buckets with water from their old tank at the moment.

Of course, I need your opinion and ideas. I'm pretty much a novice at fish- and aquarium-keeping; the only tank I have is a little three-gallon tank with a betta, and I haven't yet started to venture into the great big world of fancy aquariumkeeping. This is definitely a huge project; chances are I'll spend all of tomorrow just getting the tank clean. Ew.

Answer
Wow Kat! What  job that must have been! I'm really glad the guy at least gave it up to someone who cares about the fish.

Here's what I would do;

Empty the tank and dispose of the gravel. Rinse all the decorations and get a new filter if the old one doesn't run. If the old one runs, just clean it out really well and get new filtering media.

Be sure to change 25% of the water twice a day in the buckets the fish are in until the tank is ready. Use regular tap water but be sure to use a water conditioner. Also be sure the new water is the same temperature as the bucket water. This helps avoid shock. They've been in some pretty weird water for awhile so fresh clean water is foreign to them. This will also help them adjust to the new tank water slowly without having to float them bags for a long time.

You are right, once you get the tank ready it is a good idea to acclimate the fish. Ten minutes is plenty of time before you release them. Bags can't hold much oxygen so it isn't safe to float them very long. Since you will have already been replacing part of their bucket water they won't have a problem adjusting. Temperature equalizing is the main thing here. It will be the same as the tank in 10 minutes. Don't release the bagged water into the tank though. Net the fish from the bags and release them. That water will have lots of stress hormones and ammonia. The less of that in the tank, the better.

If you aren't sure about compatibility, take some of the questionable fish to your local fish store and donate them. Or, they should be able to tell you what they are if you don't know. It might be a good idea anyway because the tank has to go through the break-in period and it may have too many fish for it to do so safely.

Here is a link to my article on new tanks to help you through that part;

http://www.xanga.com/home.aspx?user=Expert_Fish_Help

At Your Service;
Chris Robbins