Can I keep Zebra Danios & Guppies in a tank with no heater?

[trance89]

Hi everyone, I'm new to these forums so I'm going to keep a long story short. I have a 20 gallon long tank which I need to restart my fishless cycle because I thought my heater was going to explode or something and I panicked and turned off filter and everything. Turns out there was just calcium buildup on the heater and white flakes were coming off. Anyway I've read too horror stories of people's heaters exploding and killing all of their fish and worse, so I want go without a heater completely if possible.

My aquarium temperature ranges from 65-72F without the heater in my tank. I was wondering if I would be able to keep about 6 zebra danios and 6 fancy guppies in this tank. Also are there any other type of fish that would be able to survive in these conditions (besides goldfish)?

 

[Colin_T]

Hi and welcome to the forum

Yes zebra danios and guppies can live in water at temperatures between 65-72F (18-22C), however fancy guppies will be more prone to stress at the lower end (65F) while they adapt to the cooler conditions. Once they have been in the cooler water for a month they should be fine.

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Fish kept in cooler water don't need to be fed as often so only feed them once a day after the filters have established.

While the filter is establishing, only feed them a couple of times a week and do a 75% water change and gravel clean the substrate 4-8 hours after feeding. You should also monitor the ammonia and nitrite levels while the tank is cycling and do a 75% water change and gravel clean the substrate if you get any reading above 0.

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I would not add any new fish until the filters have established. Before I recommend fish for the tank I would like to know the tank dimensions (length x width x height) and the general hardness (GH) and pH of the water. That way I can suggest fish suitable for the tank size and water chemistry.

You should be able to find the GH on your water company's website or by telephoning them. If not, take a glass full of tap water to the local pet shop and ask them to check the pH and GH of the water. Write the results down (in numbers) and post them on here.

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Aquarium heaters do not explode. I have had 1 heater glass crack in 40 years of fish keeping and that was due to me forgetting to turn the heater off before I did a water change. The heater was still turned on while I drained the water from the aquarium. This left the heater out of the water and when I added new water the hot glass cracked due to the cooler water being added to the tank.

If you get a reasonable brand of heater (Rena, Fluval, Eheim, Hagen, etc) or any aquarium heater with a 12 month (or longer) warranty, you should be fine. Just remember to turn it off 10 minutes before doing water changes and turn it back on after you have filled the tank up.