Emergency: New owner, fish dying!

[zaichev]

I bought two healthy betas last night. A large tank in on the way, shipping from amazon, with a filter and heater. At the fish store I bought a .5 gallon tank with a divider and that's their temporary home. I bought two plants, pebbles, and some medication droplets. I also put chlorine treatment in, as I'm using tap water.

They loved it last night, were swimming around, etc... but this evening it was very cloudy. So I took the fish out, cleaned it, put tap water in, brought it to room temperature, put drops in, and finally, put the fish in.

They just went from active to completely lethargic. I thought one was dying. They just sat at the bottom of the tank, would fly up for air, and sink back down. I poured out some water so it wouldn't be so hard for them, and poured some of their old water back in, hoping the bacteria/nitrogen cycle would be corrected.

I know I've made some mistakes here: my question, how do I avoid them, and how do I fix this? At the moment they are barely moving. They just sit around up top. I've put a very hot snake necked desk lamp over them, hoping to give them some "warmth" and they seem to like it?

[Pataflafla]

Change the water 100% every day and keep things dark for them. Once the new tank gets in, rinse it thoroughly along with anything else that you are putting in the tank. Once it's set up, try and maintain a constant 78-80 degrees for them since they're tropical fish.

In the mean time, make sure the water temperature you're changing them to is the same as what they're currently so you don't shock them.

It's not uncommon for bettas kept in poor conditions to go downhill after changing water sources and quality.

Did you acclimate them to both temperature and water source before releasing them into the .5 gal? If not, it could be shock from either of those and you'll just need to let them sort it out. Dark, warm, and quiet will help them out tremendously.

[zaichev]

Why dark? I've been putting a very bright, warm light on them.

[Pataflafla]

Dark so they can relax and stay calm.

Their natural environment isn't clear water, so natural light is dim at best. A bright light and clear water is very straining to the eyes and stressful if they cannot get away from it.