Heater Broke... Julli Cory Now Dead, Worried For Tetras

[ariastelle]

Title basically says it all. I have had an Aqueon 10 watt heater that has worked really well for my 5 gallon tank (keeping it at around mid 70's) for my two Glofish tetras and one Julii Cory. Unfortunately, I was on vacation for the weekend and my heater broke -- leading me to come home and see my three fish all at the bottom, very lethargic, and the thermometer showed sub-60 readings. I immediately did a 50% change with slightly more warm water to raise the temperature and my tetras seemed to be alright, but my catfish was flipped over sideways and barely breathing. I quarantined him before I went to sleep, and he seemed to be doing a little better and was more active, but was found dead in the morning (RIP Greg). I have bought a more reliable 25 Watt heater that is arriving tonight with much better reviews, and I'm shocked and outraged that that heater broke on me in such a vital time. 
 
My tank has optimal levels (0 nitrite/nitrate), right now is around 62F because the heater isn't here yet, ~7 pH, no chlorine, ideal alkalinity. The only additive I am using is API tap water conditioner when I do my water changes. 
 
I am wondering if there is any current risk for my tetras before my heater comes in. They seem to be doing alright but are swimming closer to the bottom than usual. I would also appreciate any advice you can offer about installing the heater and allowing my fish to get adjusted (should I just install the heater when it comes, or should I put them in a smaller tank and put them in later?)
 
I am very saddened by the loss of my catfish and I sincerely hope this will never happen again. Thank you for your help! 

 

[Far_King]

I would install the heater straight away when it arrives although it may take some time in bringing the temperature back up.  In a tank that size there's not much you can do when equipment fails.  In a larger tank you could have the option of some redundancy and have two heaters running.  I've done this on my display tanks in the past, knowing that either is sufficient to heat the volume of water.

This is overkill however and what has occurred just seems like bad timing as it happened when you were away.  The temp right now is a good few degrees lower than they're used to so they are most likely just trying to conserve energy.  I'm sure they'll perk up when the tank is back up to temperature but they may have become more susceptible to disease in the short term.
 
Just keep a close eye on them all.

 

[ariastelle]

I would install the heater straight away when it arrives although it may take some time in bringing the temperature back up.  In a tank that size there's not much you can do when equipment fails.  In a larger tank you could have the option of some redundancy and have two heaters running.  I've done this on my display tanks in the past, knowing that either is sufficient to heat the volume of water.
This is overkill however and what has occurred just seems like bad timing as it happened when you were away.  The temp right now is a good few degrees lower than they're used to so they are most likely just trying to conserve energy.  I'm sure they'll perk up when the tank is back up to temperature but they may have become more susceptible to disease in the short term.
 
Just keep a close eye on them all.

 
Thanks for your comment! I immediately installed the heater and the temperature is slowly rising back up. Right now it is around 72F, but they are still swimming near the bottom and do not seem very interested in food. 

 

[Far_King]

Just leave the lights off, let the tank come up to temperature and give them time.
 
They may be a bit stressed by it as well.

 

[BaylorPerez]

my tank has 2 heaters and its a 20 gal one is a 20 gal heater and another is a submersible heater(UG heater) because i have some eels in the tank that hide on the bottom so i have the tank heaters on always. As for my eels, the heater died the other day so my other heater had to do double the work as i had to order another (UG heater). but my tetras are doing fine with the temp going to atleast 60, they will just be abit more stressed, use a stress reliever if you have one on hand to help until the new heater arrives