We really want to get tropical fish but there's a problem. In the state we live in it can get as high as low 40*C's in the summer and worse, we don't have insulation installed in our house.
Would it get way too hot for the fish even without a heater? When it gets too hot, could I even get a tank cooler for it? Are fish tank coolers adjustable for temp?
Would it be possible without frying the fish?
There are coolers for aquariums but I would spend the money on a home air conditioner. The labyrinth fish like Bettas can easily take an air temperature 35 C ; I expect the water to be somewhat cooler due to evaporation. I keep Paradise fish outside ( in the shade) at 35 C air temp. With good aeration many tropical fish should be good to 35 air temperature. I keep danios, mollies, koi , under these conditions.
Use a fan or squirrel cage blower to blow air onto the water surface. This will cool the water in the tank down, albeit at the cost of evaporation. You will have to top up the water at regular intervals, and also, this does not work well in extremely humid weather. But once you get it setup, the water will be cool as heaven for the fish.
Saltwater fish are very sensitive to temperature fluctuations, and can not tolerate excessively warm water. The larger your tank, the easier it will be to maintain a consistent temperature. Fans can help to lower the temperature a bit, but the best bet is to use a dedicated water chiller. These use a refrigerant, and have coils that drop into the filter box. I’d recommend looking on eBay or Craigslist to find one.
https://www.marinedepot.com/Chillers_for_Saltwater_Aquariums-FICH-ct.html
Tropical fish thrive between 25C and 27C. They can tolerate lower and higher temps, but 40C would kill them in short order. Aquarium chillers do exist and are adjustable for temperature. There are also some homemade designs out there. Here is one I found...
https://www.thespruce.com/diy-do-it-yourself-aquarium-chiller-2924600
Good luck - I hope you can set up an aquarium! They are really rewarding.
