You did fine. Sometime in the next few days you want to get test kits for ammonia, ph, and nitrites. They are easy to use. Most you just add a few drops of reagent to a sample of tank water and then compare the colors you get with a color chart that comes with the kit. In particular over the next couple weeks look for elevated readings of ammonia and/or nitrite. Either can be deadly to your fish. Afterwards you may want to test once a month or whenever you suspect a problem in the tank.

Lisa

Thanks for the encouragement, Lisa. I don't want to have any problems, and I do worry! The fish are like my children now. I assume that should I find any problems when I test the water, the main solution will be to change the water?

you did the right thing now dont go crazy worry about test kits and what they read you will do more harm than good in trying to make it perfect.
leave the tank for now, dont change any water for at least 2 months this way everything will get in balance. at the end of the 2 months do a 30% water change preferably with a gravel syphon (python is awesome) apply a little dechlor. im not sure what kind of filter you have but you can either rinse the old material under a faucet or replace half of the filter media if its a seperate pad/carbon type filter

Thanks Squirrel, that sounds like great advice! Alot of people are telling me to test the water, too. I bought a test kit that was so complicated and time consuming I just returned it to the store. I dont think the former owner of my aquarium ever tested the water and she had fish for years.

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You have to do water changes. You cannot leave a tank alone for two months without doing tank maintenance. That goes for any tank, unless you have a system that takes out and replaces water in the tank.

Just because someone doesn't test the water yet has fish survive does not make that person a good fishkeeper. The tests are to ensure that your fish are living in an environment free of poisons - ammonia and nitrite.

I'll let someone else fill in the rest, because I've never had a community tank before. Still, I do know that you can't just set up a fish tank and leave it alone. Like all pets, the fish and the tank require maintenance.

a new tank should not have water changes right away. the water has to become established and by doing constant water changes on a new tank is asking for trouble. granted they said the tank is used but they added new water + one gallon of old. its basically a new set up.
ive been doing this for 20 years. i have cichlid tanks south american and african, goldfish tanks, community tanks and ive even done salt water successfully.
i have the same fish for many years now. water changes are the key to success but only AFTER a tank has been established. it takes at least 6 weeks for that to happen. in a new tank the water will flucuate constantly before it all balances out, that can freak out a new fish keeper into adding a bunch of chemicals to get it right, and that is the wrong thing to do

If I'm not mistaken it's the filter and the surfaces that have the bacteria, not the water. To ensure the fishes' survival the ammonia level has to be kept at a surviveable level.

I'm not saying to do a 50% change every week. A 10% change is just fine so long as the tank is kept clean. And water tests, of course, to keep track of the cycle.

your half right. beneficial bacteria are all over the tank, mostly in the gravel. by keeping it as clean as drinking water your contantly removing the good bacteria causing amonia spikes to rise and fall constantly. good bacteria will break down amonia, all new tanks will test high for amonia the first few days, the fish survive this with no help from us, occasionaly one or two will die. its basically called the "new tank syndrome" and leaving it alone is the only cure. the more you change the water in the BEGINNING the more of this "new tank syndrome" phase you will go through only when a tank is established is when its safe to carry out monthly or even bi monthly water changes with gravel syphoning.
also be carefull with over stocking a new tank and over feeding. feed very little once a day

The test kits are necessary to monitor the cycle. Any ammount of ammonia or nitrite is deadly to fish, but it is necessary to start the cycle. It should be kept to no more than 1.0 ppm with fish in the tank. If the gravel and decor along with filter media where from the original tank setup and didn't dry out for to long some of the beneficial bacteria may have survived. This will cut the time for the tank to cycle down or it may have not stopped cycleing at all. The only way to be sure is to use test kits to confirm this. It is also a good idea to test every time you do maintainance. Tap water can change from season to season or after drought or heavy rains. pH is only a concern for delicate fish and breeding, or when nitrites build a high pH makes the nitrite more lethal. In a aquarium being cycled with fish the cycle can stall and take 3- 6 months. This varies usually because of you tap water. If you leave the tank unattended for 2 months and it is cycleing your nitrates will probably climb over 50 ppm which is dangerous. If the tank isnt cycled the ammonia will probably poison the fish if not make them very ill. My advise is get the reagent type test kits a complete set is about $25 or less. Use it daily to confirm the cycle and weekly or bi-weekly there after. A few live plants will also benefit. Java fern is usually the best starter plant because it is not demanding of proper lighting or substrate.

you can go insane with those test kits. sure its the right advice but is it really necessary? well unless your running sea world its not.
keeping fresh water fish is no science, all you need is a normal stocking level, dont over feed, do partial water changes monthly if normal stocked and bi monthly if over stocked, keep up with filter media cleaning and changing and your fish will live to complete their life span. i have fish that are over 10 years old, and the last time i tested the water was back in 1982
i also dont use heaters, but thats another story

You seem like a special case. You seem like you have a system all worked out.

Remember, though, what works for you may not work for others. It's just prudence to have a water test kit, and test water regularly. It's horrible to lose expensive fish to something as easily prevented as ammonia or nitrite poisoning.

Squirrel-- I think the test sets you are refering to are the old pH dip-strips with the pH up and down additives. You are correct they where crap. Battleing pH with those powders was temporary, especially trying to bring high pH down. Just monitoring ammonia and nitrite is important because it can be found in tap water. Some water treatment facilities even add them in their efforts to make drinking water "safe". As far as fishkeeping not science, I find it more a science hobby now than ever. I had the same opinion as you when I lived in a different part of the state, never a problem and never tested. When I moved I couldnt keep from killing a fish within 2 weeks. The well water I have now was a little different to say the least. I purchased a test set and found my cycle would stall. For whatever reason my ammonia would spike and stay, never lowering. I tried every useless product the petstores would reccomend, nothing. I read books and magazines, the books where a little out-dated and the magazines offered newer info, but not as quickly as I needed it. Most research from then started with a search on the net. I just lurked on boards,and still do,and found consistancies with advise from different ones. Anyway within 2 weeks of good advise my aquarium cycled and have started several others. I am still learning, and find I learn alot by trying to answer questions. So in my case and more often than not, fishkeeping is a science- ecology, biology, and mostly chemistry, not to mention botany. For years I thought was just an art, but chemistry taught me otherwise

The water column has very little to no bacteria. Aerobic bacteria is mostly located in the filter media and gravel surface as well as decor.Aerobic bacteria thrives in dark, aerated areas with water flow. In a UGF/RUGF situation most would be in the gravel bed near the lift tubes. This is how the Bio-wheels that marineland uses work. Plenty of oxygen, water flow and darkness from the lighting by the cover. Anaerobic bacteria is mostly in the gravel bed.

Rochester-- You can go without the tests and be fine, its your desicsion. If the fish die or start to get ill in the next few weeks to a month then I would get the test set to isolate the problem. I have found that the "Master test set" from "Aquarium Pharmaceuticals" is easy to use and has all the necessary tests. It is acurate and lasts up to a year.Actually longer but the accuracy gets tainted after a year. If you want to avoid fish deaths and disease than repurchase it. It is chemistry along with luck to get the most out of your aquarium.

i guess ive been lucky to live in areas with good water. ive lived in three states throughout my life, california, nyc and pennsylvania and all were and are public water supplies not from a well. when we were house hunting we made sure that any house we looked at didnt have well water, not that there is anything wrong with it but it wouldnt be something im used to.
im glad i dont have to go through the fuss of testing, oh but yes im sorry i do test the ph of my african cichlid tank every year or so to make sure the dolomite gravel is still producing alkaline water. dolomite gravel fades out over time. but the other tanks i just do the monthly water changes and all is well.
if there is amonia or nitrites present doing a water change will lower these levels significantly. so if these chores are kept up with, this is the reason i see no need to test. in one months time unless someone goes crazy with feeding or adding a huge number of fish then in one month things arent going to change much water chemistry wise.
my input on undergravel filters--stay far far away from them :O) they are the worst filters on the market.