so I decided to email the folks at wetwebmedia. Here's the response:
Now, do fish get cataracts? If we simply mean, can the clear parts of the eye get damaged or turn opaque, then the answer is yes. There are two main reasons. The first is physical damage. If a fish bumps into something, or repeatedly jumps out and hits the hood, is handled in a rough net, or is molested by some other fish in the aquarium, the front of the eye can get damaged, and the net result is the equivalent of scarring. Dead white tissue forms a lump at the front, obscuring vision. The second reason is infection, where the damage is caused by bacteria or a parasite (e.g., Eye Fluke). More often than not, this follows on from chronically poor water conditions, with bacteria getting into the fish and causing harm because the fish's immune system has been weakened. Now, I don't think that's the issue here because your tank sounds very good. Otocinclus are much more sensitive to water quality than air-breathing Bettas, so if the Otocinclus are fine, the Betta should be too. There are some less common reasons eyes become cloudy. One is malnutrition, specifically a lack of Vitamin A. Again, I don't think that's the issue, since the diet you're offering sounds excellent. Another possibility is chlorine, which will cause this symptom among others if not removed from the water. Assuming you're using a dechlorinator, then this isn't likely. This leaves two possibilities we can't do anything about: genetics and senility. Bettas *are* inbred and genetically quite weak, and there are lots of problems that they get that aren't obvious when young but become more serious as they age. As for senility, wild Bettas are basically annual fish. Since the fancy Bettas sold in shops are about six months of age, your fish may well be a year-and-a-half old already, if not more, if it was sitting in the aquarium shop for a while. So it could be just plain old. Sure, Bettas can live in aquaria for 2, 3 or more years, but anything over a year from purchase and your fish is well past its prime. Can anything be done? Not really; just as in humans, damage to the eye doesn't usually heal without surgical or pharmaceutical intervention, and that's not really viable here. Since fish don't rely on their eyes to anything like the degree humans do, if its vision is impaired, it will manage just fine using its other senses, particularly its "built-in radar" system, its lateral line.
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So I guess I'll just monitor him. Thanks, as usual, Deb for your support! Hopefully Corwin has a lot of life left in him!
