Mass Death

[bmxweeman]

i had 10 tetras in my tank, i bought what i thought was 10 cardinal tetras about 4 weeks ago. it turned out to be 8 as a few neons had got into the same tank. so 2 neons and 8 cardinals. when i got home from work today all the cardinals were dead and floating around the tank. the 2 neons seem fine and the rest of my fish seem healthy. my ammonia level was pretty high on sunday, around 8 ppm, but ive did 3 25% water changes since them, one a day including the one on sunday, and its down to a decent level now, around 0.25 ppm.
my other readings as of the 9th were NO3 - 5ppm and NO2 - 0.50ppm
is there any explanation? and are the rest of my fish at risk?

thanks

 

[Corleone]

Your tank isn't cycled, and ammonia and nitrite poisoning is the cause - neither should be allowed to linger higher than 0.25 ppm for any period of time. All the fish in the tank are at risk from these levels.

Review this thread on how to protect your remaining fish during the cycle:
[URL="http/www.fishforums.net/index.php?showtopic=175355"]http/www.fishforums.net/index.php?showtopic=175355[/URL]

If you do lose the remaining fish, don't get more, instead, complete a fishless cycle to ensure the safety of your future stock:
[URL="http/www.fishforums.net/index.php?showtopic=113861"]http/www.fishforums.net/index.php?showtopic=113861[/URL]

You need to do immediate large water changes - do 50% now, check in a couple hours, and continue until you have ammonia and nitrite down to acceptable levels. After that, test daily and do water changes as necessary to keep ammonia and nitrite below 0.25 ppm, until both settle to 0 consistently.

 

[bmxweeman]

it should be cycled. i used active bacteria and left it for 2 weeks just to be on the safe side i was a bit behind on mmy water changes coz ive been working my ass off recently.

 

[Corleone]

it should be cycled. i used active bacteria and left it for 2 weeks just to be on the safe side i was a bit behind on mmy water changes coz ive been working my ass off recently.

Most bottled bacteria products are junk, and leaving it sit for two weeks without performing a fishless cycle involving an ammonia source doesn't do anything. If you added the bacteria and then left it sit, any living bacteria would have died off.

The situation can still probably be salvaged, but it'll be a good idea to review those threads and a few of the other stickies on setup and cycling in the New to the Hobby section, as it sounds like you got started on pet store standard advice. Sadly, most stores put their bottom line ahead of either you or your fish - the advice here puts your fish and your enjoyment first, since we don't have any financial stake in you buying or not buying any given product.

 

[bmxweeman]

fair point. but there have been fish in th tank for about 6 weeks, surely that would constatute a bacterial cycle over a sustained period with the fish providing amonia?

 

[Corleone]

Excessive ammonia levels can stall a cycle - 8 ppm is more than enough to do this, with or without fish.

Believe me or not, but your water stats don't lie - the tank isn't cycled, and that's what killed your fish.

 

[bmxweeman]

i beleive you, just trying to get a better understanding of it. what would you suggest i do now?

 

[Corleone]

Big water changes now, try to get the immediate levels under control. Did you have fish aside from the tetras? If not, two neon/cardinal tetras won't be major ammonia producers unless the tank is quite small and it should be easy to keep levels in check from there, daily water changes are the usual starting point - just test ammonia regularly and make sure it's staying in check. Anything around or over .25, and do a water change to get it down. If it gets into the .5 to 1.0 range again, do big water changes to get it down, but with daily checking, it should be easy to keep it under .25.