How to set up a temporary Betta tank

[Puzzlea]

Yep, and if you're using a sponge filter from the main tank, it'll already be cycled. Just squeeze it into the temp tank to transfer some beneficial bacteria. Saves you from dealing with ammonia spikes.

[Flynn]

I've used a plastic storage bin before. Cheap, lightweight, and holds heat decently. Just make sure it's food-safe and hasn't been used for chemicals. A lid with holes is a must though, these guys are jumpers.

[bronzeleaf]

Monitor the temp closely. Small tanks fluctuate faster. A 25-watt heater should work for 2.5 gallons, but check it every few hours to be safe.

[cargobear]

If you're in a pinch, floating a bag of their current tank water in the temp tank can help acclimate them. Just don't leave them in the bag too long.