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Close to a year ago, I had a battle with a case of hemmorahagic septicemia afflicting the entire school of peppered corydoras in my 30g. The disease was fatal and not one cory survived. The irony was the other inhabitants of the tank (danios) went relatively unscathed. I posted to this board the accepted parameters of my water. I decided not to intoduce corydoras anymore because of the concern that something may be wrong with the 30g's substrate. In that span of time, up came a new 20g tank solely for peppered and panda cories.

Fast track to two months ago when my itch to introduce cories again to my 30g (after it has evolved to a heavily planted tank) came and I decided to purchase 4 heads of peppered cories. I quarantined these for three full weeks. And introduced them to their new home in the 30g. A week and a half later, the dreaded blood streaks appeared again on their dorsal fins. And again, just like last year, the other inhabitants of the tanks are healthy (3 danios and 2 SAEs'). One cory had died and the three are now in their quarantine tank. What could have led to this constant affliction of blood streaks on corydoras whenever they are introduced to this particular tank?

Water parameters:
ph- 8
ammonia- 0
nitrite- 0
nitrate- 5mg/l
dgh- 8
dkh- 4

I do weekly 50% water change and gravel vac.
And a variety of food fed to the fish. From flakes, bits, sinking tabs, frozen brine shrimps to frozen bloodworms.

usualy blood streaks are from ammonia posioning.

are you sure your test works?

Also, 50% weekly sounds a little excessive, i personally feel it disturbs the bacteria too much.

bacteria lives on surfaces , water changes dont effect it directly. any quality issues such as ammonia might trigger stress and lead to it but this is a bit odd to hit a week and a half after being introduced. 4 cories in a heavily planted 30g would be hard pressed to produce enough bioload to push the plants and the bacteria beyond thier limits.

what type of substrate is in the tank? any chemistry difference between the QT tank and the 30g? do you run CO2 for the plants? any ferts? what species of cories are these and what were the last ones?

sorry to pound questions at you but these will help me and others try to narrow down the similiarities of this time and last time.

(edit: just read it again to find they were pepperd corries sorry about that, no need to answer what species they were )



Last edited by Sin in Style at 07-Apr-2005 18:41

It might be something PH related... Perhaps the plants, CO2 or something else are the causes of the PH shift..

Victimization,

My test kits are working okay. New stocks from Aquapharma. And on doing a 50% water change, I have known a lot of hobbyists who do that and have not had any problem.

SinInstyle..

I have the pea sized substrate in this particular tank. Ammonia and nitrite tests in both the quarantine tank (when the cories were still in it after newly purchased) and the 30g are of the same. And so were the ph levels.

I do weekly Seachem Fluorish and Seachem Iron ferts work on the planted tank. And likewise root tabs inserted every three months to the substrate. No CO2 injected.

hmm no difference. gotta be something different. maybe the ferts are causing stress. the gravel sounds fine being peasized it shouldnt be to large or to small to bother them.

err sorry im stumped i honestly have no idea. nothing foreign...maybe painted decor that might be flakeing off?

SinInStyle,

Just like you. Am just as stumped. The surviving cories are doing okay as of today in their QT. I plan to have them there for the next three weeks and continue to observe them.