You need to take immediate action to get and keep ammonia under 0.25. I'm amazed any of your fish survived at 8, let alone all of them - some of your fish, particularly neon tetras are quite delicate and usually drop dead at the slightest hint of problem. Some gouramis are also highly sensitive, though tiger barbs are tough as nails.
Your tank is cycling, and ammonia does permanent gill damage to fish, while nitrite suffocates them but does less permanent damage (this should also be kept under .25). With such a massive stocking, this will mean many water changes, possibly several a day. You might not be recognizing signs of stress, but they're likely there. Activity doesn't necessarily mean healthy - and in some cases heightened activity itself can be a warning sign.
Take a look at this thread for some information on what you're fish are going through right now:
http
/www.fishforums.net/content/New-to-t...eady-have-fish/
Next up, you need to look at stocking. The tiger barbs generally won't mix well with angel fish or gouramis, which have long fins that often prove irresistible to nippers like tiger barbs. Next, angelfish need a tank at least 18 inches tall when full grown, and shouldn't be kept in less than a 29 gallon or similar tank. Four is too much for that, though. They'll also eat neon tetras, though being raised alongside neons from a young age, they usually accept them (but are known to eat any new neons added later, only accepting the preexisting shoal). Depending on the gouramis, they could get anywhere from 2 to 26 inches long. Do you know what kind they are?
Anyway, your tank isn't cycled, but when the cycle is finished, there's a number of rules for stocking, but by all of them, you've got a tank that will never be stable. Generally in a newly cycled tank, the limit is 1 inch of adult size per gallon.
15 neon tetras: 22.5"
7 Tiger barbs: 21"
6 gouramis: I'm going to assume they're dwarf gouramis: 18" If they're pearl, opaline, threespot, moonlight, or blue, 30", and if they're kissing gouramis, around 60"
4 angel fishs: 20"
Total of 81"
For comparison, this is actually slightly more than I currently have in my 55 gallon tank, though it's comparable to my long term plans for the tank.
In an established tank that's been stable for several months, 1.5" per gallon is usually reasonable. 2" with very good filtration. You're currently shy of 7 inches, and need to look into rehousing most of your fish, or even all and going with a
fishless cycle, after which you could stock reasonably.
You can also cross post this to New to the Hobby. You'll get more advice there, and it's where the best sources of help on the forum like Miss Wiggle and backtotropical frequent.
