Hi Joe,
WELCOME to TRT!!!!
Right, like Jeff said, Goldfish aren't "tropical fish" for the tropical fish tank. They produce a slime that isn't compatible with your tropical fish, also.
The tetras work well. One betta (not two males, as they will fight with one another) will work fine.
It sound to me like he's rushing the bioload on the tank.
Also, get your own test kit and do the testing yourself... imho.
Watch the ammonia levels and if they rise, do a quick partial water change... too many fish will cause a sudden rise in ammonia levels.
Have some large mystery snails and live plants to keep it clean.
What's your filtration system? Undergravel? With some pwr heads for water movement? A charcoal canister to polish (clean) the water?
Keep it away from a window to prevent
algae growth on the glass.
Too much fish food will add to the waste (rotten uneaten fish food) that will eventually add to the bioload and possibly kill your fish, or deplete oxygen in the water which harms/kills your fish.
I would start with a couple 3 fish, then add a couple at a time with 2-3 weeks in between so the good bacteria has time to develop and keep up with the system.
Show us PICS!!
My angels, way back when I had a f/w tank, did well with live producers such as mollies, guppies, swordtails, platys, and then non-livebeareres such as
neon tetras, zebras, and others I can't remember the names of. I overstocked my tank (I was a kid and a teen-ager) and lost fish every now and then.
Good luck!
