Salty Q&A: Is My Lionfish Going Blind?

Bright aquarium lighting is sometimes implicated in causing blindness, especially in lionfish (Pterois spp.)QuestionI have a volitans lionfish that’s been in my 200-gallon tank for over two years, and lately it has begun to act like it can’t see. At feeding times, it makes an effort to grab food that’s drifting by but usually misses—like it can tell that food is in the water but can’t see it well enough to get it in its mouth. Is there a way to tell if this fish is actually going blind versus having some other health problem? – Submitted by Sean Myles Answer Thanks for your question, Sean! In his book The Salt Smart Guide to Preventing, Diagnosing, and Treating Diseases of Marine Fishes, Jay Hemdal addresses the issue of blindness in fish—specifically the subtle symptomatic differences between a fish that is going blind and one that is actually ill to the point of becoming moribund. Here is that particular excerpt from his book, which I think will answer your question better than I can: Blindness A very common symptom reported by home aquarists is that one of their fish has become blind. This, more often than not, is a result of a fish becoming ill to the point that it is moribund (close to death) and is not just blind. Basically, a fish that bumps around the aquarium, runs into the tank sides, and ignores food may not be blind at all; it may just be dying

Fish Disease Symptoms Aren’t Always What They Seem

It’s important to strike a balance between quick intervention and overreaction when it comes to marine fish disease symptomsMost marine aquarium hobbyists keep a close eye on their fish for certain tell-tale signs of ill health. And that’s a good thing, since quick intervention in the case of fish disease can often be the difference between life and death for the specimen(s). On the other hand, we do need to be cautious about overreacting to every suspicious visual or behavioral symptom because sometimes these warning signs may not be what they seem. Remember, if misapplied, medications and therapeutic protocols for fish can do considerably more harm than good. It’s important to have a fairly high degree of confidence in your diagnosis before proceeding with treatment. That means you have to guard against misinterpreting normal behaviors or forgetting that more than one problem can cause similar symptoms.To help illustrate this point, here’s a sampling of symptoms that may or may not spell trouble for your fish depending on the context: Flashing If you’ve ever been through a major outbreak of Cryptocaryon irritans, no doubt the sight of a fish turning on its side and scraping its body on the rockwork causes your heart to skip a beat. And, indeed, flashing is a potentially worrisome symptom. However, this behavior doesn’t automatically signal the presence of a parasite or other problem

Treating a Sick Marine Fish? First Do No Harm!

This fish is mildly emaciated, which could be a symptom of internal parasites if it were feeding normallyWhen a fish in our care gets sick, it’s a perfectly understandable impulse to want to throw every cure we can lay our hands on at the problem. But sometimes rushing ahead with a medication or other treatment can do more harm than good. In the following excerpt from his book The Salt Smart Guide to Preventing, Diagnosing, and Treating Diseases of Marine Fishes, author Jay Hemdal explains why the Latin phrase “Primum non nocere” (“First, do no harm”) is so significant when it comes to administering treatments to sick fish.When the cure is worse than the disease With some fish diseases, a proposed cure may actually be more damaging than the illness itself. In human medicine, this is called the iatrogenic effect, where the proposed cure causes its own serious problems. To avoid this, aquarists must always be aware of the Latin phrase “Primum non nocere,” or “First, do no harm.” Problems in developing an appropriate disease treatment can range from treating an aquarium with a medication or dosage that ends up being lethal to the fish to procrastinating due to indecision, again with fish loss as a result. In between these two extremes are using products that simply do not work as advertised, treating for the wrong disease, or trying too many different treatments. Double check the dosage and stock up Always double check your dosage calculations before adding any medication to an aquarium. Some medications can be toxic to sensitive species, notably ionic copper and chloroquine
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