New cory problems

[nik_n]

So this week I set up my new 60l planted community tank. I decided to go with a fish in cycle, as this is a method I used successfully in the past. I bough 6 corries yesterday, and after acclimating and introducing them to the tank I noticed two were looking weaker than the others. I went back to the store, because I thought they accidentally gave me sick or dying fish, but the manager said that they could have gotten stabbed by the other in the bag. I heard about this happening and was aware of corydora's "venom" if you will. I did a water change, tested the water and fed them and let them accustom to the tank overnight. In the morning I noticed that both corries seemed to have regained some of their colour, one of them has moved around the tank but isn't schooling with the other, and the other, who was breeding heavily is more or less on the same spot. I did another 80%water change today and tested the water. I will continue to test and change the water everyday for a week until the tank cycles.

Unfortunately I cannot afford to set up a hospital tank and treat this fish, but I hope it's not necessary. If I keep changing the water and feeding the corries foods such as frozen bloodworms and green beans, is it likely that both fish will recover? I really come to enjoy these fish and hope to breed them in the near future. Any advice would be appreciated.

Tank peramiters
NO2-1mg/l
NO3-50mg/l
pH-6.8

 

[Byron]

Regardless of having been "successful" in the past, cycling a small tank with fish is probably going to cause permanent issues even if the fish survive initially. Nitrite (NO2) above zero is very dangerous, so do daily 60-70% water changes until this is zero over successive days. Nitrate at 50 is certainly going to harm cories long-term, so reducing this with the daily water changes will help.

I strongly recommend floating plants. Cover the surface. These are fast growing and take up ammonia more rapidly than the nitrifying bacteria, and they have an almost inexhaustible capacity. This alone is the best solution here.

I would suspect the above to be the issue. While the bit about pectoral spine/toxin is certainly true, this is much less likely unless the fish were badly treated during the netting/bagging process. There is no cure for this toxin, but the fish so far as I have been led to understand the issue would most likely be dead by now, and all of them. I would concentrate on the cycling issue, as this for cories is very serious.

 

[NoodleOfDanger0]

The one that is swimming but not schooling, might be stressed from having been unwell or it might not like the other cories. I had one that just hated other cory catfish. I had a school of 5 other cories for him to hang out with and a golden Chinese algae eater in the tank and my cory would swim with her and none of the other cories. He would sit in a corner and refuse to eat when I had him in a hospital tank after he got cut on one of my decor pieces. I eventually had to rehome the Chinese algae eater because I was downsizing my tank and she was too big for the tank they were going into. I gave her to a friend and soon observed that Bubbles, my cory, was sulking in the corner, refusing to eat. I reached out to my friend and asked her if she could take Bubbles too and as soon as he was back in a tank with her he was swimming next to her and eating again and was just a much happier fella. This is them in my friend's quarantine tank.

Some cories just don't like other cories. Or maybe mine was broken but I've heard from other friends who have had similar issues.

 

[nik_n]

Regardless of having been "successful" in the past, cycling a small tank with fish is probably going to cause permanent issues even if the fish survive initially. Nitrite (NO2) above zero is very dangerous, so do daily 60-70% water changes until this is zero over successive days. Nitrate at 50 is certainly going to harm cories long-term, so reducing this with the daily water changes will help.

I strongly recommend floating plants. Cover the surface. These are fast growing and take up ammonia more rapidly than the nitrifying bacteria, and they have an almost inexhaustible capacity. This alone is the best solution here.

I would suspect the above to be the issue. While the bit about pectoral spine/toxin is certainly true, this is much less likely unless the fish were badly treated during the netting/bagging process. There is no cure for this toxin, but the fish so far as I have been led to understand the issue would most likely be dead by now, and all of them. I would concentrate on the cycling issue, as this for cories is very serious.

As stated above, I do 80% daily water changes. I also add nitrifying bacteria. The tank is already heavily planted with epiphytes and stem plants. I do agree that adding floating plants would help massively and I plan to purchase some on Friday.
I do agree with you, that the toxin my not be the cause of these issue, since the other corries are schooling and swimming properly. This also indicates that that water perimeters are not harmful for them, but regardless I will continue to water change and test for the next week.

 

[nik_n]

The one that is swimming but not schooling, might be stressed from having been unwell or it might not like the other cories. I had one that just hated other cory catfish. I had a school of 5 other cories for him to hang out with and a golden Chinese algae eater in the tank and my cory would swim with her and none of the other cories. He would sit in a corner and refuse to eat when I had him in a hospital tank after he got cut on one of my decor pieces. I eventually had to rehome the Chinese algae eater because I was downsizing my tank and she was too big for the tank they were going into. I gave her to a friend and soon observed that Bubbles, my cory, was sulking in the corner, refusing to eat. I reached out to my friend and asked her if she could take Bubbles too and as soon as he was back in a tank with her he was swimming next to her and eating again and was just a much happier fella. This is them in my friend's quarantine tank.

Some cories just don't like other cories. Or maybe mine was broken but I've heard from other friends who have had similar issues.

I definitely heard of some corries not schooling with others as much, but this doesn't bother me as long as they are healthy. I'm planning on adding more fish down the road, some of which my be more corries

 

[outofwater]

The one that is swimming but not schooling, might be stressed from having been unwell or it might not like the other cories. I had one that just hated other cory catfish. I had a school of 5 other cories for him to hang out with and a golden Chinese algae eater in the tank and my cory would swim with her and none of the other cories. He would sit in a corner and refuse to eat when I had him in a hospital tank after he got cut on one of my decor pieces. I eventually had to rehome the Chinese algae eater because I was downsizing my tank and she was too big for the tank they were going into. I gave her to a friend and soon observed that Bubbles, my cory, was sulking in the corner, refusing to eat. I reached out to my friend and asked her if she could take Bubbles too and as soon as he was back in a tank with her he was swimming next to her and eating again and was just a much happier fella. This is them in my friend's quarantine tank.

Some cories just don't like other cories. Or maybe mine was broken but I've heard from other friends who have had similar issues.

That's cool, I've heard of "unlikely" and "not advised" pairings working out. It's always a gamble mixing fish, but somehow some make it work. Animals of all types always surprise me with their quirks and preferences.