Cory's Dying

[Mickfender]

Help please,albino corys dying for no obvious reason. I added 6 young albino corys they are about 4 months old to my tank 8 days ago,2 days later 1 died, i replaced this with another 1 from same batch in shop. They seemed ok swimming all over the tank, today i could only see 5 searched the tank could not find it anywhere, then about 30 mins after this could only see 4, this time i found it dead. There was nothing wrong looking at it no fins or bits missing. The only thing ive done was add 10 assassin snails 3 days ago. The tank is 125 ltr, tetratec ex700 filter, well planted, been running for more than 6 months, it has 6 sterbai cory, 8 serpea tetra and 8 endlers. My stats are ammonia 0 nitrite 0 nitrate 30-40 and ph 7.8, this has been the same since i added fish. Any thoughts on this most welcome thanks Mick.

 

[the biffster]

does the shop keep there fish in RO water ??

 

[mattlee]

does the shop keep there fish in RO water ??

if acclimatised in the correct manor this will not have any effect on the fish

 

[Mickfender]

Just found 1, so it was only 1 that died. Not sure about the ro water or not in shop. I acclimatised them slow over the course of nearly 2 hours, left the bag in tank for about 30 mins before adding small amounts of tank water to bag about every 10/15 mins for the next 90 mins, then netted them 1 at a time into tank.

 

[elisew]

I`m sorry you`ve lost one of your Corys.
I wish I could help but I found one of my Albino Corys had died yesterday too, another one seems to be swimming mid-level of the tank and seems to have no idea of where he`s going, not sure if he`s gone blind

There was no signs of anything wrong with the one that died yesterday and there`s nothing visible on the 'blind' one either and I`m really puzzled as to why this is happening.
I have just invested in an RO system as the Rams and Corys are kept in RO water at the store, it`s an option I`m prepared to try to stop my fish from dying so often. Like you my tests results are fine, wc and tests are done regularly.

I`d be interested to see if anyone can find an answer for you.

 

[mattlee]

plenty of fish are transfered from ro to tap water every day so i dont know why people keep bringing this up. its probably more of a shock from fish kept at pH 6 at the lfs going into pH 8 at home but again if done correctly there should be no ill effects. i have transfered discus from ro water at a low pH to tap water of pH 7.8 with no issues as i took plenty of time over it and didnt rush it.
corys are pretty hardy fish from my experience with them and i cant see this killing them. also the op doesnt state that they are kept in ro in the first place. there are many reasons for fish to die shortly after being introduced into a new home but if done properly it wont be acclimatising.

 

[Mickfender]

Now the 1 i thought was dead is playing dead, it lies in 1 place for a long time not moving looking dead, first it was in a plant head first for more than 30 mins i thought it was gone went to get it out and it swam away looking ok, stayed with his mates for a bit then lay on sand not moving again for ages, moved off to a plant leave,played dead for 20 mins, then went straight to sand and lying still again very strange as these guys have never acted like this before. only 3 of them seem to be acting normal 1 hardly moving at all and 1 near the top of tank all the time not gasping for air or breaking water surface just swimming fast over glass at top and not coming down.

 

[Inchworm]

Hi Mickfender

There's also the possibility that your corys have bacterial infections. Since this is the most common problem corys have, I would not rule it out. Some bacterial infections are fast acting and some take time to develop. So since your fish are new, it might be either a situation you bought them with or one they caught in your tank. This is why it's always best to confine new fish to a quarantine tank for the first few weeks.

Since you mentioned adding assassin snails, I wonder whether you have a snail problem in the tank. If so, it could be due to overfeeding which could also lead to the growth of harmful bacteria in the substrate. If corys are sick, one of the best things you can do is keep the water clean and fresh. I hope they recover for you.

 

[hillmar77]

Maybe take a look at GH and KH values too. I've had a few Cory deaths that didn't seem natural! I know not a lot of people talk about osmoregulation in the majority of the forums out there but could explain alot of deaths that doesn't make sense on healthy fishes. Here is a good read:
Osmotic Stress and Shock

Occurs when fish are kept in water with inadequate mineral levels (too high or too low). Osmotic stress affects more seriously fish whose natural habitat is rich in minerals and who are kept in an aquarium with a low mineral level, as osmotic gradients (difference) between the internal fluids of the fish and its surrounding environment (water) increase. Such fish have a less effective osmoregulation than those who are physiologically adapted to water with a low mineral level. That is why they are not able to cope with overloading of osmoregulation. Osmotic shock can be a result of a breakdown in osmoregulation due to inappropriate chemical composition of the water. It can also be caused by increased permeability of the skin resulting from a disease or trauma. Osmoregulation enables fish to maintain the proper balance of salt and water in the body, which is necessary to create optimal conditions for various physiological and biochemical processes. In all fish species osmoregulation developed in a way that enabled them to maintain the proper balance of salt and water in the water with chemical composition found in their natural habitat. If osmoregulation is disturbed due to adverse conditions (osmotic stress) or a sudden change in the chemical composition of water (osmotic shock), fish might not be able to physiologically cope wih it.
Chronic osmotic stress can eventually result in fish’s death and osmotic shock can cause death very quickly.

 

[Mickfender]

Thanks for the replies, the 5 albinos seem to be acting like themselves again. I thought 2 had died but 1 was just hiding and not moving for long periods but that seems to have stopped now. I am still keeping a close eye on them to make sure. Yes got a few pond snails, came with plants i bought so i got assassins to keep them in check,to move around under the sand,helpful with any harmful gas build up or so im led to believe and because i think they are good looking little snails.Cheers Mick