Black aro fins??

Since moving into my 2000L tank the black aro has been growing fairly steadily, from ~12" to 18-19" since July. One thing I've noticed is the strange growth of his fins, more so the dorsal, tail and anal fins. It is as if the rays have been growing faster than the membrane between them. The water is good (very low hardness and TDS, pH ~6.8-7, 26-7C, 0 ammonia and nitrite, <20ppm nitrate), and the finnage of the other fish, including Geophagus and angels, is fine. I was wondering if the membrane would "catch up" to the rays, if it were caused by a growth spurt, but it appears to be becoming more exaggerated. The fish appears healthy, eats well (shrimp and hikari sticks), and the other fins appear unaffected. Any suggestions???

September;



Yesterday;

Bderick67 said:

Definetly not typical growth, looks like some sort of fin rot. Just odd that it doesn't seem to affect the rays.

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or the other long-finned fish! I'm reluctant to treat it without having some idea of what is going on though. It doesn't seem to be affecting the other fins, and the membrane doesn't seem to be eroding any further, if anything the rays are just getting longer.

No I haven't tried salt, and usually try avoid using it, but I think in this case you're right it could be worth a should. I'll have to pick some up, actually a lot of it!

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Wondering if I should bump the temp up a degree or two? The controller is accurate to 1C so switches on at 26C and off at 27C, the probe is in the sump so the tank fluctuates between about 25.7 and 27C.

No such thing as Lowes in NZ.

Thanks tho, I'm sure there is somewhere local to buy bulk salts.