Massive Die-Off

[jwjager]

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Tank size: 125 gals
pH: 6.8
ammonia: .50
nitrite: 1.0
nitrate: 20
kH: 300
gH: 120
tank temp: 75F

Fish Symptoms (include full description including lesion, color, location, fish behavior): fish are just dying, guppies grouping at top of tank in the corners.

Volume and Frequency of water changes: 1/3 every 2 to 3 weeks

Chemical Additives or Media in your tank: chemipure in canister filter,foam and poly filters with bio-stars and ceramic bio tubes. hang on filter has prepackaged filter paks.

Tank inhabitants: 1 bristle nose pleco, 8 neons, 3 yellow snails, 25 pepper corys, lots of swords and guppies. in the last two days I've lost 6 large Siamese algae eaters, 2 goldfish and 50 or so guppies and now the swords are starting to die.

Recent additions to your tank (living or decoration): added a new marineland emperor 400 filter to system two weeks ago

Exposure to chemicals: none


tank has been set up for 3 years with no problem, i have a xp4 canister filter and have just added the emperor 400 as a backup and to help with the bio load. i have replaced all the filter media and have done a 1/3 water change but guppies are still dying. the neons are swimming around like there is no problem and the corys are acting normal. somne of the corys are mating and i have cory eggs on the side of the tank now. I live in sw missouri. the tank has gravel substrate with plastic plants and some java moss. there are two 300w heaters and a 12 airstone. any ideas would help. thanks

 

[Kitty_Nin]

Ammonia and Nitrite should be zero, which would be why your fish are suddenly dying. If you lost two goldfish and 50 or so guppies and still have 'lot's', then I'd say your problem is massive overstocking.

 

[dstev]

1/3 change of water every 2-3 weeks sounds a bit too long in my eyes. After 3 weeks ammonia is very likely to be building up.

How about trying to alternate between 10-15% and 25-30% water change every week?

*edit* Also probably got something to do with the fact that you have put a new filter system in. Did you take any sponges out of your old one and add them to your new one?

 

[WILDER]

If you replaced all the filter sponges the tanks cycling again.

is the tank 125 gallons, or litres.

Can you post full fish stock please.

Immediate water change and increase aeration.

Fish will die in bad water quality.

 

[jwjager]

Thanks to those who replied. All the swordtails and guppies have died. the neons and peppered corys are fine with no losses. I understand that the tank was way overstocked, that was one reason i added the second filter. The nitrite levels were at 1 and the ammonia levels were at .5, so I'm not understanding the ammonia spike idea. I've also been under the impression that neons and corys are the first fish to die with bad water quality but they are doing fine. T^he corys are even mating and laying eggs, I'm guessing from all the water changes lately. Would adding the second filter change the parameters that much? Once again thanks for the ideas. This time I will control the fish population better and do more frequent water changes.

 

[WILDER]

A second filter helps with the fish load. Once it cycled.
It's best to over filter a tank.

Water changes twice a week, and gravel vac once a week.
More effort is required when a tank is overstocked.
Keep an eye on water stats.
Reduce your stocking.