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Fish/Black Spot/Outlining on Female Betta Picutre Update


I recently purchased a female betta fish at a local Petsmart, and have had her for about two days now. She looked really quite healthy, and has appeared to do well in her new tank. The water was conditioned and quality tested before adding her to the tank to make sure that conditions were optimal. Temps are 74-76 F, and the tank is a filtered 2.3 gallon bow-shaped desktop aquarium. The water is somewhat cloudy at the moment, but it appears to be clearing. However, I have noticed a small (<1.5 mm) black spot on her right side behind the gills. Additionally, on the same side not far in front of the tail fin, there is some black outlining of the scales in a patch about the size of a pinky fingernail (very much like that of a pineapple betta). It only appears in that one area however. The rest of her body looks clean and healthy as does her fins. It has been quite a while since I've kept fish, and I am really new to tabletop aquariums and betta fish. I am not sure if the is normal coloration or perhaps a sign of disease. I would attach an image but because of the shape of the tank, it is impossible to get the level of detail to see the areas in question. Any help would be greatly appreciated. Thank you.

ANSWER: Hello Andrew,
Run water tests for NH3, NO2-, and NO3-. These will help diagnose the problem depending on which are (or are not) present. It sounds like a small parasite resulting in poor water quality to me, but I can't tell you for sure without a picture. Go to your local fish store and ask about antibiotics for "gill flukes". I'm almost sure that's your issue.
Sorry I couldn't give you a more helpful answer!

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Betta Fish with Black Outlining 1
Betta Fish with Black  

Betta Fish with Black Outlining 2
Betta Fish with Black  
QUESTION: Dear Will,
Thank you so much for your help. I have finally been able to get a good picture of the areas in question. Any help would be really appreciated. Thank you for your time.

Hello Andrew,
Sorry for my slow response. Based on the way the melanophors (cells that give fish color) work, I think it's possible those spots are just the melanophors acting up. This is harmless, but it's a good indicator of environmental stress of some kind. My first guesses would be that the water temperature is too cold, or there is too much stress to the fish during normal maintenance, or there is too much stress coming from outside the tank.
Also, if it is a parasite, by now there will be a significant problem and this will be obvious by behavior. If the fish is not acting very sickly, just check the water temperature (should be in the 75-85 range), try fewer partial water changes (rather than full changes), and make sure the tank is in a low traffic, quiet area out of direct sunlight.


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I can answer questions relating to the scientific aspect of the hobby (fish ecology, biology, genetics, etc. ), aquacultural and breeding aspects, and have experience with nearly all "brackish" fish in the trade. I also have lots of experience breeding fish, like angelfish, tetras, cichlids, and various livebearers. I also have lots of experience with many freshwater fish, especially "monster" fish, like stingrays, arowana and Saratoga, cichlids, catfish, etc. Please ask questions about anything except for true saltwater (reef) tanks.


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