Weak tetra

Question
I have a small tank that has about 12 gal of conditioned water in it (not sure of total capacity, there's a couple inches of air and about 1 inch of gravel). We've had the heater, filter, air pump on for about three or four days now, and today we went to the aquarium and bought 5 neon tetras and a mystery snail. When we got back we floated the bag for fifteen minutes, added some tank water, floated it for another 20, and then netted the tetras and snail into the tank.

Four of our tetras seem fine and are schooling, but one is just floating there vertically, head up. He only flips his fins occasionally to propel himself to the surface where he opens and closes his mouth. If (rarely) he's swimming he's usually on his left side, and he doesn't swim very far. What might the problem be, and will he be able to get better? For now we have him sitting in an open-top container suspended in the tank but isolated from the other fish.

I didn't think it could be new tank syndrome because it happened immediately when we put him in, so ammonia etc would have all been zero. I hope you can help us.

Answer
Hi Bel
I'm glad you're familiar with the new tank syndrome/cycle process.  And you're correct, most likely ammonia is not a factor at this point given the size of neons.  However, they are not the best fish to start a tank with.  One reason, because they are so small, they really don't put out much waste and such to start the cycle process.  And, neons are very sensitive,  due to inbreeding, overbreeding, and just the nature of them combined.  It's very common for them to die off just from the move from the store to your tank.  I've read before if you want a school of 6 neons, you should buy at least 12 to account for the early die offs.....So, I would venture to say, either the neon was sickly before you bought it and maybe didn't notice it, or just the stress of the move and the new water quality of your tank is what's wrong with it.  Not sure if he'll make it or not, it's hard to say with neons.  Usually once they start acting poorly, it's downhill for them though, at least my experiences have been that way.

What I would recommend in the future when you buy new fish, float the bag like you did for a few minutes to allow the water temperature in the bag to adjust to your tank, then add a bit of water, wait a few minutes, then add some water, etc. etc.  I end up filling the bag of water up all the way.  I usually take a good 30-60 minutes depending on the type of fish, to allow them to slowly adjust to the ph and temperature differences.

Honestly, I would probably recommend returning all the fish and do a fishless cycle on your tank.  Or, return them and get some heartier fish to cycle the tank with.  Or, if you know someone with a disease free fully cycled tank, you could use some filter squeezings from that tank, and put it directly into your filter to almost instantly cycle your tank.

Good luck with your new tank!

Christy