Stocking my 56 gallon tank

Question
Karen,
Thank you for taking your time to answer all of these questions that everyone has!!!

I have a 56 gallon tank, dimensions are 36"long, 18"wide, and 24" tall. We got the tank a month ago. We set everything up and like the pet store guy said to do, we let it run for 5 days then added some fish. Everything was going great with one Bala Shark, one Red Tailed Shark, two of what the guy at the pet store said were glow fish, two Dalmatian Molly's and three Serpae Tetras. I was told that it was only necessary to do a 20% water change every couple to three weeks. Two weeks later I did a 50% water change and a pretty thorough vacuum of the river rock that's in there. All fish were doing fine after that until three days after the cleaning we we went back to the pet store and were convinced to get two Guppies, and three white-colored tetras. The morning after we introduced the 5 new fish both Guppies, two of the white Tetras, two of the Serpae Tetras, both Mollies, and the Bala Shark were dead.
After that I started doing all the research I should have done before trusting the pet store guy.
I have begun doing more frequent water changes and we are thinking about starting to re-stock the tank......this time the right way.
We are thinking about 4 dwarf gouramis, 2 discus, 5 angelfish, 5-7 serpaes tetras, and 4 molly's.
Should these fish get along well?
Would this be enough of each of them?
In what order and timing should they be added?

Thanks for everything!!!!

Answer
Hi Carrie,
I wish petstores would get their information up to date! ;-)

I'm glad you did the research, cheers for that! And the more water changes the better as I and many fishkeepers have found out. Never again believe you should only change 20% once a month.

With re-stocking your tank. I'd go very slow and gradual. Start with the hardiest fish and work your way down. Which I believe the Serpae Tetras fit the bill quite well. Put them in and wait a couple of weeks to see how they do. You should also test your water during this time for ammonia, nitrites and nitrates. If any of the former two are rising, that means your aquarium has not yet cycled and you'll need to do a large water change and give your tank more time. If your fish seem to be suffering, along with a water change, you can also add a water conditioner that neutralizes ammonia and nitrite. While not an excuse for water changes it does help when its at a critical point.

The next fish in line would probably be the Mollies if this were my tank. Then the Dwarf gouramis, angelfish, and then discus. While these fish you mentioned are all reasonably peaceful. Many people would say that discus are not going to do well with those other fish and they should only be kept with small tetras or rasboras. While unfortunately I've never kept discus (I will soon) from the many many articles I've read I know they always say that if you're going to keep discus, you should build the tank's stocking scheme around their needs. Its possible the mollies may nibble at their broad sides and the serpaes may nip their fins, and the angelfish may out-compete the discus. This is only an possibility. Because you get mixed opinions about such things like that. For example you are often warned not to keep Angelfish and discus together while somebody else claims they do great. It probably helps if the fish are raised together of course. We can't really predict how any fish is going to behave with another species. The best you can do is go by the guidelines because I feel there aren't really any 'strict' rules.

With that thought out. I would give intervals of about a week or two between the fish, but this depends on how your water tests out. You can have your own test kits at home but you can bring a sample to your petstore but make sure to ask for the exact readings. It's safe to add fish when the ammonia and nitrites have dropped to zero. Sometimes you may get a "mini-ammonia/nitrite spike" when you add some new fish but that usually goes away shortly after.

BEST OF LUCK!
Karen~