[soco1125]

I got up this morning and turned on the light to my 55g... only to find that all but one of my glowlight tetras had suddenly died overnight! The one remaining didn't look too good though. He was very pale and listless. I managed to get a pic of him before he expired:

This is one that had already died:

All the other fish in the tank seem to be fine. The water tests out normal and there have been no major changes recently. Could the glowlights have succumbed to old age? They were all purchased from Wal-Mart over 3 years ago. Should I medicate the other fish just in case? If so, what should I use?

Thanks!

 

[soco1125]

I can't believe I forgot to list all that stuff... I know better. Haha, what a dummy I am! Sorry about that. Anyways:

Size: 55g (~208L)
pH: 6.0
Test kit used: API liquid freshwater pH
Temperature: 80*
Filtration: very large sponge/ powerhead combo
Substrate: gravel/Fluorite mix
Plants: java fern, sagittaria, java moss (lightly planted)
Other decor: 2 pieces of Malaysian driftwood (1 large, 1 small), 2 glass bottles (cleaned & boiled before being put in the tank a month ago)
Last water change: 30% 4 days ago... at least 20% is done weekly
Other fish: 12 black neons, 1 angelfish, 1 rainbowfish
Feedings: 2-3 small feedings throughout the day; alternating of tropical flakes, freeze-dried brine shrimp, freeze-dried bloodworms, and an occasional treat of live feeder guppy fry

I'm afraid I can't give an ammonia/nitrate/nitrite level because I ran out of that tester and have not been able to get to the LFS 40 miles away because of the snow. I know I need to get it... I promise I will ASAP.

The tank had cycled for 2 months. The filter had been used in an already established tank (my other 55g which had been running for 3 years) to create bacteria growth on the sponge. It and some gravel from the older tank was also added to this new one. After it ran empty for 1 week, a few feeder guppies were added. After another 2 weeks, the rainbowfish was added. Once the new tank had cycled for 2 months, the tetras and angelfish were moved from the old 55g tank to this new one because I was changing the substrate. Temperature and pH are the same in both tanks. The little feeder guppies were short-lived once Angel found them. All the fish had been in there for 6 weeks and all appeared very healthy. They were active, in good colour, and eating well (although the glowlights' colouring had been fading a bit in their old age). All of these fish had been living together since the day I got them. The angelfish and glowlights is/were about 3-4 years old. The black neons are about 1 year old and the rainbow is 4-5 years old. There is no aggression shown to the tetras by the angel; she usually just ignores them. The others are still doing very well, which is why I suspected that the poor little WalMart glowlights had simply lived out their lifespan.

 

[soco1125]

I did think afterwards that of course the glowlights were older than 3 years... don't know why I'm so dense lately. I also don't know where I got the impression that they only live 3 or 4 years... probably misread it somewhere. So I guess their real age is a mystery.

I did a 40% water change after removing the dead fish (we're on a private well, so there isn't any chlorine or anything in the water). Everyone else seems to be just fine. The tetras are chasing each other around and Angel and the rainbow are begging for food as usual. I think I'll start slowly moving them back to the old tank now that it's thouroughly settled in with its new substrate and plants.

I'll be able to get to the LFS later today and pick up a new test kit. I will also see what I can do about adding another filter since apparently the [eBay] seller of this one was incorrect in stating that it was adequate for up to 90g.

Thanks for being so patient with me everyone