Will my lionfish’s fin grow back?

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David Wolfenden shares his advice to a reader that is worried that their lionfish's fin won't grow back.

Q) I have a 7.5cm/3in Volitans lionfish. Its first and third pectoral fi ns are shorter than the rest. Please could you tell me whether they will grow back? Apart from that the fish is eating well and seems fine.

STEPHEN DALRYMPLE, VIA EMAIL

A) DAVE WOLFENDEN REPLIES: If the fish is eating and behaving well, that’s a good sign, and it’s one less thing to worry about. The first thing to consider is the possible reason for the shorter fin rays. Is this a recent injury or has the fish suffered some trauma previously? Or has the fish looked like this since you’ve acquired it?

It’s possible that this is simply a genetic deformity from birth, in which case there is nothing you can do. As it doesn’t appear to be affecting the fish in any way in terms of feeding and behaviour, it isn’t a welfare issue.

Alternatively, the rays could be shorter due to some kind of physical trauma — perhaps the damage was done during handling or shipping, for example. This might be accompanied by tearing of the delicate tissue attached to each ray, so have a good look to see if you can note any torn or shredded fin tissue. Without seeing the fi ns, it’s hard to say what the outcome is likely to be but in general if the rays are broken near the base, then they are unlikely to grow back much, if at all. However, if they are broken near the tip then there’s a good chance that the fish can mineralise new ends of the fi n rays and regrow those sections of fi n.

Either way, the best course of action is to keep a close eye on the fish for the Will my lionfish’s fi n grow back? moment. It’s feeding, so just monitor it and see what happens. If the fish has had an injury, you’ll want to watch for secondary infections and/or a change in behaviour. Lionfish really are very hardy so hopefully there won’t be any issues, but it’s still worth watching out for.