Pic request; Adult L18 vs L177

[David R]

Trying to figure out which variety to order a group of, L177 has nicer colours but L18 gets bigger. Google image results are varied and inaccurate, so does anyone have pictures of mature examples of each?

Also, how big a difference in terms of size/growth rate have you found in aquariua?

[Silurus]

I would have assumed that the adults of both varieties would look the same, being the same species. At least that's what the subadult pic of L177 in the Cat-eLog seems to indicate.

[David R]

I would have assumed that the adults of both varieties would look the same, being the same species.

I guarantee you and I don't look the same, despite both being adults of the same species. ;)

I know they have both been classified as Baryancistrus xanthellus, but there are still two (?) distinct forms of the species from different locations. Unfortunately it looks like when the profiles for L177 and L18 were merged upon being classified as the same species the pictures weren't kept separate or labelled as to which form they're of. I'm unsure how much of a difference there is at adult size, and that is what I am attempting to find out.

[Jools]

I've nothing to suggest L018 and L177 have different adult sizes and am unaware of a consistent difference. I'd like to understand more.

Jools

[David R]

Jools, not sure if the historical data is still available, but IIRC even the PC cat-e-log listed L18/85 as having a larger max size than L177 before the profiles were merged when the species was described.

There is also this Shane's World article; http://www.planetcatfish.com/shanesworl ... _id=382The

In the Cachoeira Cutevelo not far from Altamira, in one of the favourite rapids of the fish collectors, we covered a group of three rocks with a large net and caught about 20 adult L018s of over 30cm length out of the cracks in the rock, which was a good indication of the concentration of the fish population here.

There's also this FNZAS article, and I'm sure there would be references in older text books that pre-date the species being described. I believe it is generally accepted that L177 grows to ~7-8", while L18/85 can get to 12-13", as shown in the pics and article. Strange how one form is bigger than the listed maximum of the described species and the other smaller...

[Jools]

It's a bit more complex than that.

Firstly the Sl given is for the species, as the species contains the two L-numbers, the max size is whichever was the larger. Bear in mind the SL given in the cat-elog is the largest reasonably verified SL. What is the origin of the the "fact" that L177 is smaller than L018? Was it the Planet data sheet? If not, then what?

Now, we have to deal in guesswork. Large L018 can be collected relatively easily, larger L177 would take a lot more effort because they are further away. If they looked really different, there would be more of a market for them but we don't see them - is that because no one collects them or because they look very similar to L018 as adults? If they look different, is the IBAMA positive list a barier to collection?

@Janne, might be best placed to be able to help with these questions.

Another issue with these plecos is very few people keep them alive for long enough for them to grow to adult sizes. The larger ones are imported large. Again, L018 is going to be a lot easier to do this with.

So, I'm happy to record that the L177 strain has not been recorded at larger sizes but it's too much of a leap (without more data) to say they don't get bigger given they're classified as the same species. Of course, we should dig into this, it is not beyond doubt that they are not one species.

The original thread title is great, and what we should focus on. Someone who has grown up both L018 and L177 and can say what they do and, better still, show it with pictures. I (or anyone!) could have a look at the 2011 paper and see if it gives sizes for what can be shown as L177.

BTW, does anyone know the sizes of the fishes in this picture?



Jools

[David R]

Fair points, I guess wasn't basing my last post on hard scientific data.

I agree completely that they haven't been kept long enough in captivity to know fully the differences at adult sizes, almost all of the pics I've been able to find of adult are pics of fish being caught in habitat. Hopefully I'll be able to answer this question in ten or so years time!

It looks like I was mistaken about my id anyway and what I though was L18 is actually L81, so these are the fish I'll be ordering, on the wholesalers list as "Queen Gold Nugget", unsure whether they're L18 or L177...