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How to Keep Your Fish Happy and Healthy in a Heat Wave


 It feels like it's been HOT summer after HOT summer, and while we are all trying to push the limits of what our air conditioning system (and budget) can handle, it's important to recognize that your fish will be battling the same.

While most tropical fish can handle pretty big swings in temperature (as long as they are gradual), some temperature-sensitive aquatic creatures Axolotls just can't handle the heat.

If you're like us, we'd rather brave the heat than let our fishy friends be uncomfortable. But if your thermostat is not winning this battle, here are some strategies to cool down your aquarium.


Method 1: Eliminating Heat Sources

Get rid of things that produce heat!

  • Swap conventional tube lights for energy-efficient LED lights to reduce heat emission. Try to figure out the bare- minimum your lights need to be on to keep your plants healthy. Other than that, switch your lights off!
  • Opt for a sponge filter with a basic air pump to minimize heat compared to powerful filtration systems.
  • Consider turning off extras like UV sterilizers when unnecessary. They give off more heat than you'd think!

Method 2: Strategic Relocation

Smart placement can make a significant difference:

  • Move the aquarium away from direct sunlight to a shaded area.
  • Keep curtains closed during the day to prevent indirect sunlight from heating the tank (and the room!)
  • Avoid positioning the aquarium near heating vents, exterior doors/ walls, ovens, or dryers. Is your tank sitting on a kitchen counter? Kitchens tend to be the warmest room in the house year- round. Think about relocating to a cool bedroom or office for the summer.
  • Remember that cool air sinks, and hot air rises. The fish tank you have on the second story on a top shelf near the ceiling will be a lot warmer than that tank you keep in the basement.

Method 3: Harnessing Evaporative Cooling

Emulate natural cooling through evaporation:

  • Remove the tank lid to encourage water evaporation and heat dissipation.
  • Use mesh lids designed for Herp tanks to prevent escapes.
  • Enhance evaporation with surface agitation using air stones or sponge filters. I have even been known to aim a small clip fan over the top of my tank. You'll have to do more frequent water changes and top ups, but it makes a difference!
  • As a bonus, increased surface turbulence aids gas exchange and prevents oxygen depletion!

Method 4: Employing Insulation

Minimize heat intrusion with insulation:

  • Cover tank walls with Styrofoam or reflective foil insulation. I have used that reflective bubble wrap stuff on three sides of my aquarium for most of the year. Kudos if you had the foresight to layer a sheet of it under the bottom of your tank before you filled it.
  • Remember those water- top ups and changes you had to do? Refill your tank from the cold water tap, and this insulation will help the tank warm up slower. Don't forget to add dechlorinator!

Method 5: The Chiller Solution

For persistent overheating, consider a chiller. For most fish we all keep, there's really no need to spare this hassle and expense, but you may feel the investment is worth it.

  • A chiller regulates temperature by circulating water between the aquarium and the chiller unit.
  • Research and choose a suitable chiller based on aquarium size and needs.
  • While costlier, chillers offer consistent and precise temperature control. Once and Done!


By following a comprehensive plan that considers your aquarium’s surroundings and your fish’s requirements, you’ll make a cozy and steady home for your fish during the hot summer days.

Keep cool!


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