Eye problems and erratic behavior

[David Ellsworth]

I have a 20L tank with 12 rainbow shiners. I realize I have neglected water changes for quite some time and I believe I have been over feeding looking back at things.

I noticed something was wrong when one fish had problems with his eyes and was acting erratic. He swam strangely and bumped into the driftwood and plants. He doesn't shoal with the others and I think he may be blind now. This is because when I netted him out he didn't know the net was there and wondered into it when he was bumbling about. I tested the water immediately and my nitrate was off the scale of 160ppm. Here are the test results:

PH: 7.3 (two months ago it was 7.74 which is closer to normal with my water)

temp: 73

Ammonia: 0.25

Nitrite: 0

Nitrate: 160 +

TDS: 656

 

I looked online and did a rapid nitrate reduction water change I found that targeted salt water hobbyists. I drained the tank to 20% and then filled it to 40% with dechlorinated tap water 2 times. Then one more time I drained the water from 40% to 20% and then filled it up full.  My water after the changes:

 

PH: 8.49

Temp: 73

Ammonia: 0.5 (I have chloramine in my tap water so some ammonia is present)

Nitrite: 0

Nitrate: 5 ppm

TDS: 652

I will keep an eye on the tank and the fish in question still is by himself, but looks like he is picking around the moss and substrate for food. So I think he may not know where the others are in the tank?  Also one of the pictures looks like there is some discoloring on one of his gills. Here are some pictures of him and the last picture is of a healthy looking tank mates for comparison.

 

 

Edited November 17, 2020 by David Ellsworth

[Ken Dyer]

Sounds like you are on the right track, I would just continue the observation and make sure they keep improving. As for the vision impaired shiner if you add him back with his school I would just try and make sure he isn't being out competed for food with his challenge.

[David Ellsworth]

He stays upper midwater and swims around in circles, I'm guessing to avoid the hardscape in the tank. I may need to separate him from the others cause they are all fast during eating and he is clumsy. Maybe a breeder box will give him time to find food. 

 

Could the high nitrate have caused this? Did it just stress him out so he has caught  something? I saw one fish persistently agressing another's head and eye area, could it be physical damage? 

[Ken Dyer]

3 hours ago, David Ellsworth said:

Could the high nitrate have caused this? Did it just stress him out so he has caught  something? I saw one fish persistently agressing another's head and eye area, could it be physical damage? 

Any of those are possible. I know some fish will go after each others eyes if they get hungry, and I have had fish damage their eyes on decor like driftwood when spooked. I wouldn't think 160ppm of nitrate would be enough to do such direct damage, but different species definitely have different levels of sensitivity so it is not outside the realm of possibility.

I do know while out fly fishing I have caught one eyed fish before, so at least game species can survive and make do in the wild with a single eye. My best advice would be clean water and make an effort to ensure your little buddy is getting to eat. I would likely scatter food across the top and make an effort to target feed in the area where it is if it doesn't seem to be getting food.