Broken heater = dead fish..now what?
I came home last night to find the fish in my 10 gallon behaving very strangely, and also noticed a few were missing and presumed dead. When I pulled the tank out to see what was going on, it was warm to the touch. I took the temp of the water and found that it was up to 93 degrees and the light on my water heater was still on! This tank had 4 harlequins and 1 catfish. 3 of the harlequins were dead the 4th looked on its way out.
Anyway, I replaced half the water and removed the dead fish, and miraculously the two remaining fish seemed to react immediately.
My question is this: Will water temp this high kill all the beneficial bacteria that has built up? I'm wondering if I'm going to need to recycle the whole tank from scratch again before adding more fish. I wasn't crazy about the stock I had before and am thinking about just putting in a lone betta next, but want to make sure that the tank is stable first.
No, the bacteria will survive.
Unfortunately, heaters do malfunction. I had much the same thing occur several years ago with one of mine. The only way to hopefully prevent this is to buy the very best heaters, and going with a higher rather than lower wattage. For some reason, at least in my experience over 20+ years, the 50w heaters fail much more frequently than 150w and 200w heaters. The heater is the single most important piece of equipment in the aquarium; failure can cost the lives of fish, as you have seen. A filter failing or the light would never be this tragic. So a good heater is worth the money.
Byron Hosking, BMus, MA
Vancouver, BC, Canada
Something we all need to remember: The fish you've acquired was quite happy not being owned by you, minding its own business. If you’re going to take it under your wing then you’re responsible for it. Every aspect of its life is under your control, from water quality and temperature to swimming space. [Nathan Hill in PFK]
It's also worth a small investment to hang or float thermometers and check them daily to insure that you catch a malfunctioning heater as soon as possible. One day of 93 degree heat would not have killed your fish but several days would have.
sorry for your loss.
30 g FW planted:corys, ABNP, blue angel, harleys, zebra danios, pair kribs, & nerite snails
15 g FW planted: crown tail betta, neons, snails
90 g FW semi planted: EBJD, congos, apple snails
90 Gal Journal: http://www.aquaticcommunity.com/aqua...ad.php?t=93939
Fishless cycling: http://www.aquaticcommunity.com/aqua...ead.php?t=5640
Cycling with fish: http://www.aquaticcommunity.com/aqua...ad.php?t=36492
A bad heater caused a tank crash in my reef tank, you are lucky that you caught yours in time to save anything. I then bought an expensive heater as Byron suggested above - it has a light that glows red or blue when the temp is high or low, and green for good. And also ditto what Byron said concerning your BB - they will be good to go, but with fewer fish in the tank now your BB population will drop a bit as there is not as much ammonia available to them. Any population is limited by the food available to it. If you only are going to replace with a betta, you have no worries, but if you are going to stock more fish, keep in mind you will have to do it slowly.