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Anyone know anything about clamped tail fins?


New Member

Have been away from the forums for a while due to life taking over (it still is, but...), we've got a small(?) problem with a couple of our apisto's.

We have a general community tank with a couple of male and 3 female Apisto's, all A. Agassizii (2 double red and the others different but we don't know what type!).

We've had no problems for months, but one of the males and females have just spawned (3 days ago inside the internal filter bracket of all places), now one of the males (we don't know if it was the spawning male or not) has clamped his tail fin as you can see in the picture of him below. Said gentleman, seems to be eating fine but now hides and doesn't move much. Another female (not the egg-layer) has also got the same clamped tail fin and is hiding around the filter.

BTW, the egg-laying female ate them all, but it's her first go at it, so not unexpected!

Does anyone know if this fin clamping is related to the spawning, or whether it's likely to be an illness? Should we quarantine them/treat them or is it likely just a behavioural thing?

Thanks in advance for any help.


(BTW couldn't see anything in the rules about pictures, but if we need to remove this picture or link to one externally, just tell us!)


I've found that clamped fins are generally a harbinger of illness or serious distress, although I wonder if in this situation the spawning triggered some elevated territorial aggression and this is the non-spawning male. Were there any recent changes in the water parameters? Any signs of scale damage on this fish?


New Member
Hi ChuckinMA thanks for your reply. Our water parameters haven't changed at all and there are no signs of damage (see the picture above - his other side is the same!).

Weirdly, he was (or maybe still is) the alpha male!

It's really strange, the behaviour in the tank amongst the apisto's does seem to have totally change since the spawning, I'm wondering whether to do a redesign of the tank and change the layout to see if that forces them to re-choose their territories and see if that calms everyone down. In fact, the female that spawned looks the best she ever has and seems to be merrily zipping round the tank happy as larry - it's the others that are generally keeping out of the way - though only this male is clamping his tail fin and actively hiding as much as possible!


Well-Known Member
5 Year Member
Keep watch for any signs of rapid breathing, stringy mucus in the feces, loss of appetite, bumps or sores on the head or body, redness in the nostrils or anus, abdominal swelling or thinning, or other possible disease symptoms. Clamped fins might be due to social stress from the aggressive female, but like Chuck says it can also be an early sign of disease.


Active Member
5 Year Member
Fish with clamped fins sitting on the bottom is not a good sign. Normally, healthy fish tends to go to the top to hide instead of sitting on the bottom.