Why would a fish randomly go blind?

[Volturi21]

I have a small snapper that is now blind. It completely relies on it's sense of smell and feel. I feel awful. It never had a disease that I could see. Maybe something was going on internally but this is so random.
Any ideas as go why?

I almost feel like putting it out of it's misery but I wouldn't really know how to go about that without feeling awful. It's interesting to watch the instincts to kick in though. The snapper is lying low to the bottom of the tank and navigating by placing it's snout on the sand and swimming that way. I guess its using the bottom as a safe haven. In the wild I'm sure in the water column a small snapper would get picked off immediately by a predator.

 

[Recty]

If you really want to humanely kill the fish, a lot of people just scoop them into a ziploc bag of water, or a tupperware container and put it in the freezer, they just basically go to sleep.

Have you ever treated the tank while the fish was in it? Some people have reported copper as causing blindness.

It could have had it's eyes burned by ammonia while shipping, but that's doubtful it would cause permanent blindness.

How long did you have it and how long did it take it to go blind?

 

[LukFox]

In addition to Recty's excellent suggestions, I've heard of flukes and even infection (that you might not be able to see) causing blindness. Those would be worth treating for if symptoms fit before killing it I'd think. Only thing on euthanasia is freezing is now considered inhumane; clove oil or a heavy blow to the head seem to be best.

 

[JHemdal]

I have a French angel that got bitten by a green moray and is mostly blind - it finds its food by nosing along the bottom, is that how your fish feeds? I've considered euthanizing this fish, but it is doing well, actually growing. Its eyes have gotten better over the years....

"Only thing on euthanasia is freezing is now considered inhumane" - that is just an opinion, not a universal truism.

I'll frequently suggest that technique if I think that the act of euthanizing the fish is going to be harder on the owner than on the fish - can't suggest to a squeamish person to pith a fish, even close oil will cause spasms in some fish, looking a lot like terrible agony. Putting a fish in a tupperware container, out of sight, may be better for some people - and there is no evidence that I've ever seen to show that fish feel any pain during this process. Personally, I use MS-222, but that is not always available.

Jay

 

[LukFox]

I have a French angel that got bitten by a green moray and is mostly blind - it finds its food by nosing along the bottom, is that how your fish feeds? I've considered euthanizing this fish, but it is doing well, actually growing. Its eyes have gotten better over the years....

"Only thing on euthanasia is freezing is now considered inhumane" - that is just an opinion, not a universal truism.

I'll frequently suggest that technique if I think that the act of euthanizing the fish is going to be harder on the owner than on the fish - can't suggest to a squeamish person to pith a fish, even close oil will cause spasms in some fish, looking a lot like terrible agony. Putting a fish in a tupperware container, out of sight, may be better for some people - and there is no evidence that I've ever seen to show that fish feel any pain during this process. Personally, I use MS-222, but that is not always available.

Jay

Ah I remembered reading a study at some point, but if you haven't heard of it it must not have been valid. (If this comes off as sarcastic I really don't mean it. I value your information very much and would think you'd have come across it at some point.)

I do know it was once considered humane in reptiles, and for the same kind of thinking. "The body just shuts down, they fall asleep, and eventually die painlessly." This has been found untrue, and it was once recommended by veterinarians but now is forbidden. It wouldn't really surprise me if we eventually find the same is true for fish. Even if it remains an unknown, I'm not sure how we can call it euthanasia because it is unknown. It's easier on the owner for sure, and they can do what they want in the end, but it shouldn't be labeled as a method of euthanasia because we simply don't know if it is. I guess I jumped the gun on calling it "inhumane," but I was remembering a study I'd read quite a while ago. Apologies for that.

 

[JHemdal]

Alexa,

There was a flurry of "do fish feel pain" studies a while back - yes or no, it depended on who was funding the study - the anti-angling groups were behind at least one of the "yes they do" studies.

I won't use eugenol (clove oil) on fish - a sore tooth perhaps, but fish are really bothered by it. Metomidate was another choice, but it lacked any anesthetic properties, you could euthanize fish with it, but they were aware up until the end.

Many years ago, I observed a researcher euthanize a series of trout with a "heavy blow to the head". This was awful - some fish required multiple hits, and even then nerve twitches made it difficult to know if the fish was dead or not. Blood and tissue went everywhere, and there was at least one smashed finger.
I once tried to pith a toadfish with a scalpel - my hand slipped and I got jabbed by its venomous cheek spine - ouch!

MS-222 is my first choice, freezing is my second.....

Jay

 

[LukFox]

Thank you for the information, Jay. I was always under the impression that clove oil is pretty painless and easy on the fish, and simply knocks them out in low doses (good for trimming puffer teeth, I remember). However I have never used it myself.

On a small enough fish (not trout size for sure) I think it would be a little hard to mess up stomping on it, though... But that's not easy on the keeper at all and I probably couldn't do it.

 

[Volturi21]

I thought I replied back to this thread but I guess it didn't post or something. I put the snapper out of it's misery with a quick blow to the head. I didn't want to freeze it. It was very difficult for me after I killed the snapper. I felt awful all day but I didn't want to see it in misery anymore.

 

[Recty]

I would so much rather freeze a fish than actually strike it hard enough to kill it.

 

[Volturi21]

It was a quicker death

 

[Recty]

I know if it was me dying, I'd rather slowly cool down and die of hypothermia (you basically stop caring and feel nothing) than receive multiple blows to my cranium.

 

[Volturi21]

I know if it was me dying, I'd rather slowly cool down and die of hypothermia (you basically stop caring and feel nothing) than receive multiple blows to my cranium.

This is subjective. Let's agree to disagree. It was one quick blow to the head. It was over in a second. I don't know if I could have caught the fish and put it in the freezer knowing it was dying a slow death. I probably would have taken him back out of the freezer before it died and put him back in the fish tank. Trust me, it was hard to do it but it had to be done some way. I preferred this way. You can prefer yours.

 

[Recty]

True that

 

[colbar]

Volturi21 I feel for you and although it was difficult to do, I'm sure
you now feel a bit happier. It's aweful to watch a fish in distress. I agree with you and would have done the same.