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When I purchased this little guy the seller told me that it is a L183 (Ancistrus dolichopterus), but I noticed that it has no white margin on its dorsal fin and tail, except small patches of white at the tips of the tail. Is it a L071 or what? Now, its size is about 80 mm. Sorry for unclear pictures. Any comment would help, please......

The body shape is definitely similar to L183. Wrong head shape for L71. A clear pic of the dorsal fin extended will tell whether it's L183 as they have more soft rays than any other known species.

Larry

How big is the fish? It doesn't look very small, so I'd say it can still be A. dolichopterus - they are VERY distinct in that they have a longer dorsal fin with at least 10 rays. In all other Ancistrus (that we are aware of) the number is smaller. Unfortunately, the dorsal fin isn't clear to see in your photo. The ideal way to get a shot of the dorsal is by holding the fish out of water - it will hold out all it's fins as a defense.

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Mats

Thanks for your advice, pleco_breeder and MatsP.
Yesterday I tried to catch it, it took ages pursuing it all over the tank and still I couldn't catch it....
But fortunately I still could notice that it has only 9 dorsal rays, on the other hand unfortunately I couldn't take a picture of its dorsal fin. So, now I'm sure that it is not a L183 indeed. If it is not a L071 either, is it still possible that it could be a L180 or L213?

Are you sure you are counting the rays correctly? It can be quite hard to count them - and you need to count at the bottom, before they branch.

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Mats

@MatsP : Yep, I counted at the bottom. So what is the closest ID for my ancistrus?

So is it 8 soft rays and 1 hard ray, or 9 soft and 1 hard ray?

The "normal" Ancistrus dorsal is 7 soft rays and 1 hard ray, so yours is "unusual" in any case. May be an odd A. dolichopterus, or something unknown. I'm sure someone will correct me, but I don't believe there is any described fish with 9 dorsal rays - it's either 8 in total or 10 or more.

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Mats

I'm 99% sure that your Bristlenose male is Ancistrus L180. Ancistrus L213 is a very
similar species but L213 has a very compact body with a wider head and the space
between the adipose fin and the base of the caudal fin is small almost non-existent.
L213 also have an overall blueish tint when they are well conditioned and they
have distinct trailers on both the top and bottom of the caudal fin or what one
could call a lyretail.

Here is a photo of my wild L180 male and even the bristles look quite similar.


This is a wild Ancistrus L213 which shows the compact body shape compared
to a 1" F1 juvenile Ancistrus L183.

MatsP wrote:So is it 8 soft rays and 1 hard ray, or 9 soft and 1 hard ray?

The "normal" Ancistrus dorsal is 7 soft rays and 1 hard ray, so yours is "unusual" in any case. May be an odd A. dolichopterus, or something unknown. I'm sure someone will correct me, but I don't believe there is any described fish with 9 dorsal rays - it's either 8 in total or 10 or more.

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Mats

Trivia: Cordylancistrus platyrhynchus can have 9 or 10 soft dorsal fin rays. However, I do not know if A. dolichopterus shows this same possible variation.

@jackster: It looks like a L180 indeed, thanx....

Thanx also for everyone who give their opinion on this thread....