# My fish all died when I added a heater



## harts (May 20, 2009)

Hi all, I have read a lot here so far that has been helpful but I would like to gather some thoughts on what has happened in my tank. I have some idea but dont want to risk missing anything.
I have had 2 male guppies in a small tank with no heater for almost a year with no worries. I changed them into a larger tank so I could add some more fish and other bits to make it look nice, they have been in there for 2 weeks all happy, I added some neo tetras, 2 black widow tetras and a another fish thats a bottom feeding fish (cant remeber its name statrts with C).
They have all been in there a week and it was looking fantastic until a added a heater. The water temp was at 19c a bit cold for the Tetras but the guppies had been fine with it, I set it low to bring up the temp slowly. I put it in late sunday night the got home Monday night and 3 neons where dead, it took only a few hours for the another 3 to die and the guppies where sitting at the top of the tank. The next morning on guppie was dead and the other is sic and looking a lot darker in color just sitting on the bottom. I removed the heater and changed about 20% of the water and the remaing neon and black widow seamed to liven up so after a day I put the heater back in and over night all black widows died and the last neon. The bottom feeder is happy as and the other guppie is only just hanging in there but everything else has died. They all looked fine with no signs of bloating or anything, when the died the slowed down and the would just get blown around by the water then swin a little before giving up.
Being new to this I have no idea whats up, I tried to do the right thing and put a heater in as I knew it was needed but that seamed to be the problem. I would love some advice on where to go from here so when I put more fish in everything is right.
Thanks


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## emc7 (Jul 23, 2005)

I'm not sure the heater is the problem. When heaters kill fish, usually, when you go to fish them out, you notice hot water or get a shock. I suppose a cheap Chinese heater could have toxic residue on/in it. But I think its more important that you are at 1-2 weeks after adding new fish. Thats about the time you get ammonia and nitrite from the added bioload and about the time any new diseases that came home with your unquarantined new fish start offing your old fish that aren't immune to them. Gasping at the surface can be a sign of ammonia poisoning. 

Unfortunately, you are likely to have something like this happen every time you add a lot of fish at once. Do a large water change (50%) before adding any new fish and do large water changes every few days thereafter until you know the 'mini-cycle' is over. And get a quarantine tank, every new fish from a store with a central system is a ticking time bomb of fish disease. I would wait 4-6 weeks before adding any fish to make sure any disease in the tank now has largely run its coarse.


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## COM (Mar 15, 2008)

How high did the temperature get? Unless it got above 30c (86F - I used to live in Italy) it shouldn't really have started to kill the fish. It is possible that emc7 is right that some contaminant from poor manufacturing was all over it and that is what killed the fish, but that is unlikely.

Most likely adding the heater had nothing to do with the problem, but you are attributing the deaths to the heater because they happened after you added the heater. _Post hoc ergo propter hoc._ After this therefore because of this.

Most likely your issue is due to tank cycling.


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## harts (May 20, 2009)

Thanks guys for the responses, the tank tem only got to 21, I thought it may have set something off like a desease or something. From what I read I thought it may have been ammonia as the guppies were at the top of the tank doing the gasp thing before anything started to die. I can believe how quick it took the all out. I will leave the tank go and cycle the water for the next few weeks and the try introduceing new fish 2 at a time maybe. In the mean time I will read up here for tips on how to add them and keep them happy and healthy. I really enjoying watching them. Is there any shrimp you can buy in Australia that will live happily with the type of fish I have? I wouldnt mind adding them as well.


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