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1stAquarium 01-10-2010 03:16 PM

Disappearing neons?!
I bought 7 neons a week or so ago, 3 have died already. Two had injuries - a damaged fin on one, and some sort of cut or mark down both sides on the other.
They live in a 64 litre planted and decorated tank (around 17 US gallons/14 UK gallons) with 5 WCMM, 5 golden mountain minnows, 2 cherry barbs, 1 BN catfish and numerous guppy fry. This is a temporary measure whilst I cycle another tank for most these other fish to move in to.
Any ideas what may be causing the deaths? I am doing frequent water changes, and the tank has been established for around 5 months as I read this was the minimum time to wait before getting neons. Their tank mates seem to leave them alone.

Byron 01-10-2010 05:39 PM

I wouldn't expect trouble from the other fish you mention, so what about water parameters. What is the temperature in this tank, and do you know the pH and hardness of your water? Also, did you do any check for ammonia after introducing the neons? And by plants, is the tank well planted or just a couple plants?


1stAquarium 01-11-2010 04:32 PM

Thanks Byron. The tank is not heavily planted, there are around 5 or so real plants, some java moss and a couple of plastic plants. I have just tested the water and ammonia is at 0, nitrites at 0.1, nitrates at around 20. All of these readings are in mg/l. The pH is 7.5 and I don't currently have anything to test the water hardness. The temperature is always 25-26 celsius. I didn't check for ammonia straight after introducing the neons, but I have been doing frequent water changes. Today my friend gave me his four adult neons and whilst I was putting them in the tank, I noticed one of my young neons was separated from the group behind the filter canister, swimming very eratically, looking disorientated and trying to swim upwards to the surface but never making it. I had to go out for a short while and when I came home this neon was nowhere to be seen, no floating body and upon scanning the tank I cannot see a body at all. :(

Byron 01-11-2010 06:34 PM

On possibility that occurs to me is a mini-cycle when the 7 neons went in to your 15g tank. I wouldn't expect this with even some plants, even in a 15g (larger tanks have more room to absorb these things). Nitrite above zero supports this though. Neons (characins in general) are more sensitive to ammonia and nitrite than some fish. And eratic swimming is a sign of poisoning by ammonia or nitrite, although could be something else too.

The other possibility is something wrong with the fish themselves. It will be worth observing the four neons added today. Measure the ammonia after a few hours and see what that shows, nitrite too.

How did you introduce the new fish? Did you by any chance compare their water with your tank for pH?


1stAquarium 01-12-2010 12:36 PM

I will be watching the four newest additions closely and I'll make sure to test the water again later. Yes I read that neons are very sensitive to pH changes so I tested their water before adding them and it was the same or very close. I am thinking maybe they already had a problem at the store as I noticed a few other tanks had dead or ill fish in them. I don't think I'll bother buying from there again. I just hope the latest four are okay.

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