Harlequin Rasbora (Missing eye & not eating)

[Haywire]

Tank size: 180L (approx 47 US gallon)
pH: 7.4
ammonia: 0ppm
nitrite: 0ppm
nitrate: 40-80ppm (Hard to tell with the API master test kit, but I wasn't aware this was so high. I assumed I needn't bother testing for nitrates because there are plenty of live plants and no algae, however, clearly I need to pay some attention to this)
dH: 8.3
tank temp: 26 degrees celcius

Volume and Frequency of water changes:
At least 50% every week

Chemical Additives or Media in your tank:
Secheam Prime, TNC carbon, TNC complete
Standard filter media

Tank inhabitants:
18 Neon Tetras
10 Harlequin Rasboras

Hi all,

On Saturday (2 days ago), I bought 10 Harlequin Rasboras from my local aquatics store. I also purchased 6 more neon tetras to join the 12 that were already in the tank (added a week prior).

When I got them home, I noticed that one was missing its left eye. There's no question about whether it's there, you can see through it, it's quite grim really.

I am worried about its health. I should note that all the other fish are doing really well, which I'm very pleased for. My one-eyed friend does swim about with the other fish and is usually just as energetic, but he's very slow at feeding time. When the lid opens, they all enter a frenzy and dart about. I try to locate the poorly fish and throw the food in around him, but the other fish are so fast that I often can't get him to eat. He'll go for food when it's close enough, but I worry that his senses are impaired meaning he can't find it very well. I

I'm looking for some advice on what to do as I'm unsure how serious this is. I do have a second 60L tank (which I intend to house a beta) but it's not at all set up yet. I mention this in case I need a space to treat the fish.

Thanks for your help.

 

[Byron]

A missing eye is not an issue to worry about. [Unless of course another fish in your tank is doing this, but that seems unlikely here.] There is nothing you can do to somehow "treat" this anyway. The fish will likely be fine; it is in a group of its own species and they communicate by chemical signals (pheromones) and chances are the fish will be fine and live for years.

 

[Byron]

I missed something earlier, about the nitrate, as I was concentrating on the rasbora.

Have you tested your source water (tap) on its own for nitrate? Nitrate can sometimes be present, and you need to verify this. If the nitrate is occurring solely within the tank, we can more easily handle it. And you are right that nitrate as high as 40 ppm is a concern as this is harmful to fish long-term.

And concerning the API nitrate test, you need to shake Regent #2 at least two full minutes before adding drops to the test tube. Regent #1 is OK with 30 seconds (I think that is what the instructions say), but Regent #2 must be shaken 2 minutes or the results are often faulty. This regent breaks down in the bottle and has to be thoroughly mixed.

 

[Colin_T]

As Byron stated, the fish should be fine. Just make sure it gets some food. You can feed them more often (3 or 4 times a day) and just make sure it gets something to eat. As long as there are no predators in the tank the fish can live out its days in the safety of your aquarium.

The other option is to return the fish and the shop will probably replace it and then euthanize the one without an eye.