Sick Bronze Cory.

[bigcheed]

hi all one of my bronze corys has begun to list and lie on his left hand side. he is showing no  other signs of stress or disease is activly looking for and eating his food but when he swims its like hes being pulled down towards the left and only the left. have seen him also lying on his left hand side. my corys share there tank with cherry shrimps who are a new adition but other than them nothing has changed in the tank. water peramters are all good 0amm 0nitrite 20nitrate ph7. ive had my corys the longest of all my fish. never had any trouble from them and they spawn regularly. any advice would be welcome. thanks.

 

[Byron]

Without being able to observe the fish for a time it is difficult to say precisely, but I have known corys to periodically flop onto a side.  Loaches do this too.  It may mean a health issue, but it also may not.  Observe things and see what if anything develops.
 
Some general observations.  Nitrate at 20 ppm is a bit high, and corys are highly sensitive to all forms of nitrogen (ammonia, nitrite and nitrate).  Is this nitrate in the source water (tap or well, whichever you use), or occurring within the tank itself (source being lower)?  I would want to lower this.  Not suggesting this is the issue by any means, but with the sensitivity of fish to nitrate it is something that won't help and may be easily remedied.
 
I assume foods are not an issue if spawning is regular, but avoid worms (frozen bloodworms, live worms) more than once or at most twice a week as treats.  These are very fatty and high in protein which is not good for fish long-term.
 
Byron.

 

[bigcheed]

thanks for the feed back byron. i did another batch of water tests as something felt off about that nitrate reading. lo and behold the new reading is 5ppm. tested again just to be sure and its the same. dont know how i managed to get 20ppm but i did think that was ok so thanks for putting me right on that one. my fish dont get worms as a rule i prefer brine shrimp both frozen and live as well as daphnia. they only get it once a week and its alternated for veriety. i sat and watched said fish for a while earlier and the behaviour seems to be getting worse. he corkscrewed from one side of the tank to the other before and is still resting on his left hand side. it sort of reminds of when a person has a stroke. he seems to have lost the use of the left half of his body. but is still active and ate with the rest of the fish earlier. hope it just passes like you said. thanks again.

 

[Byron]

Another possible is that the fish was injured sometime in the past, as when being caught.  Internal injuries sometimes don't manifest themselves until weeks and months later.  And yet another option is some genetic issue.  I have had the odd fish just suddenly do this, even after having it for several years.  I generally don't worry, unless it spreads or has obvious signs of something that may spread.
 
Byron.

 

[bigcheed]

after more observation it appears said fish has injured its left pectoral fin in some way. the fin itself is tucked in close to the body and there is no movment in it  at all. its quite clear this is whats causing him swimming problems. however he is still active although a little clumsy and feeding well. do i wait to see if he heals or is it cruel to let him struggle on?

 

[Byron]

The question of fish feeling pain is often debated.  I don't know, but so long as the fish is not being picked on, and is able to eat so it is otherwise healthy, I tend to leave it.  When I see a fish clearly wasting away, or being harassed, and if it is something I know will not improve (thiinking here of a swim bladder issue), I euthanize it.