Does Hemiancistrus subviridis eat snails?

[emanuel]

Hi all, have any of you ever noticed if H. subviridis L200 actively eats snails?
Leporacanthicus heterodon L172 is known to eat slugs, but I've never heard of H. subviridis.

Yet it seems to me that mine has devoured a huge amount of snails in a short time.
Until recently I had a big problem with snails, they reproduced uncontrollably and covered everything in my tank, I had to integrate a product every day to raise PH and KH, snails consumed a lot for their shells. If I didn't integrate the product, in two/three days the PH went from 6.5 to 5.3.
Then I added H. subviridis and very quickly the snails decreased, you can see the difference in the photos of my tank. Incredible the difference isn't it? I didn't make any other changes, other than removing the Vallisneria and putting more rocks in its place, but that couldn't have affected the slug population.
As soon as I inserted H. subviridis the snails really started to decrease, I was finding empty shells on the sand and unfortunately Anentome helena (killer snail) was also eaten.
At first I thought they were simply starving, as the big H. subviridis was a competitor to them and wiped out all the algae in the aquarium, but then when I found the killer snail shells, I started to think that c 'was someone actively eating them. Because otherwise it didn't make sense. The only possible one was H. subviridis, I didn't put any other fish besides him, immediately after putting him in the tank the snails started to decrease.
Before H. subviridis I had L236 in the aquarium; L168 and L260, Corydoras sterbai and Apistogramma hongsloi and snails reproduced en masse.

Dunno I don't know, I've never seen him actively eat snails, yet see for yourself the difference in the picture. Has anyone had similar experiences?

November 19, 2022.

November 27, 2022. It's only been eight days since I entered L200 and the slugs have gone down a lot

December 4th 2022. Change of layout, removed the vallisneria and added new rocks on the left. Now there are only a few snails left ...

[Jools]

This isn't something I've heard of before. However, it's also the first time I've seen a heavy infestation of that type of snail (one of the spp. of Planorbidae?) where plecos were introduced. Usually the snail problem is with MTS (Melanoides tuberculata) which assassin snails (correctly I think it's a whelk - Clea helena)) will control.

Did you see any snails being eaten? Are you sure it's

Hemiancistrus subviridis

and not

Baryancistrus demantoides

? The former is an omnivore, so no reason why they wouldn't eat snails but when something new like this is documented, it's worth checking.

It would be fascinating to see if the fish was removed if the snails came back.

Cheers,

Jools

[emanuel]

(one of the spp. of Planorbidae?)

Yes

Did you see any snails being eaten?

Unfortunately not, in fact it was only when I saw that all the killer snails were dead that I started to think that someone was eating the snails. Until the day before adding H. Subviridis to the aquarium I had thousands(!) of Planorbis and 15 Clea helena, then suddenly H. subviridis enters and the snails disappear, including C. helena. Only the empty shells remain on the sand, it means that someone ate them. All clues lead to H. subviridis, but they are only clues (albeit very strong), certain proof is still missing.

Are you sure it's

Hemiancistrus subviridis

and not

Baryancistrus demantoides

?

Yes yes, 100% sure, here is a photo from November when it was just arrived in the aquarium and a more recent video. Measures approximately 5 inches (12/13 cm)

It would be fascinating to see if the fish was removed if the snails came back.

It would be really interesting, but unfortunately I don't have other aquariums in the house where to move it.
I'm very curious if anyone has seen H. subviridis eat a live snail. In the meantime I'll try to observe the aquarium better to see if I can observe the moment my L200 eats the snail.
Definitely H. subivridis has the ability to eat something alive, he loves it when I give him tubifex or other live worms

[sturiosoma]

I would watch him for unusual head movements and I say this because I noticed one of my Crossoloricaria bahuja bobbing it's head up and down one day and upon closer observation I saw that it had a mts snail in it's mouth and I'm thinking the head bobbing is a sucking action, I will try to get video, but what if you were to drop in a couple algae wafers which would attract the snails and then maybe attract hemi, could be fun, and also that's a good looking fish

Jeanne

[Koi-fantast]

I have seen Apistograma take a bite on a snail, maybe Malaysan Trumpet Snail if I remember correct, and try to shake it out. I have seen 2 apr 25cm L114 eat Appel snail, 5 were gone in like three days. My two cents.

[emanuel]

I have an important update!

A few days ago I clearly saw my H. subvirdis eating a snail for the first time. A noise similar to screeching or scratching something hard (I'm not sure how to describe it), caught my attention. I looked where it came from: it was the teeth of H. subvirdis "scratching" on the shell of the snail. In a short time he sucked it out of the shell and swallowed it. Of course I didn't have time to take my camera to make a video; but now I've left my camera next to the tank, hoping I can make a video for you all the next time I watch H. subvirdis eat a snail.

[naturalart]

Thats great, looking forward to the video!

[emanuel]

I haven't yet been able to film H. subviridis eating a snail (sooner or later I will), but by holding the camera close to the aquarium, I have had success with Hypancistrus L236!
In the first video you can see one of my H. L236s making a first attempt, then he gets frightened and retreats, but soon returns decisively to his prey, only to be frightened again and never comes back. Surely at night when I'm not out front with the camera, there's nothing to scare him and he gets the job done.
The second specimen in the video (the white one), was there working with the snail in its mouth for a few minutes. Too bad that at one point it is chased away by a L168 that has its lair right there.
However, you can notice the numerous empty snail shells, the culprit is Hemiancistrus subviridis, practically that is the area where I give the vegetables. Vegetables attract snails in large numbers, so H. subviridis takes advantage of this and finds both vegetables and snails in the same dish Only in that area are there so many empty shells. I give the vegetables in the evening, in the morning the vegetable has been completely consumed and is full of new empty snail shells, so they must have been eaten by H. subviridis.
The third specimen at the end of the video is barely seen, inside its den doing the same thing as the other two.

I had the group of Hypancistrus L236 while being overrun by slugs and although they did eat them, they were too small to affect their numbers. Only when I put Hemiancistrus subviridis, which was a much bigger and hungry mouth, did the number of snails start decreasing fast.
I have had 5 Hemincistrus subivridis for a few weeks now and the snails have almost completely disappeared, even the four new specimens then eat them in large quantities.

[Kirin]

Diets in Loricariids are awfully patchy in the literature. Some we have to extreme detail e.g. Panaque/Panaqolus or detailed gut analysis e.g. Lasiancistrus caucanus. Otherwise it's often vague with generalisations of taxa so there is a level of ambiguity, it's not like some mammals where we can say what it eats seasonally, daily and depending on the sex of the animal.
So yes it is possible many are eating snails but to what level. Is eating it just consuming it through the mouth but is it digesting it? Does it assimilate it? Does it aid in digestion?
So small pest snails I think more then certain will pass through the gut based on how many feed, maybe less so I can see it going in through the gut of 'Baryancistrus' demantoides and 'Hemiancistrus' subviridis. It still could happen. Whether they are processing any of that I highly doubt, I've seen cichlids pass snails out the same way they went in. I think in the gut the snails would have passed away during that.
Do they have the anatomy to handle molluscs and snails? Maybe some molluscs but not snails. Snails generally there are a few methods to handle them but mainly prising them out the shell or crushing the shell. For prising out the shell you're looking at the mouth flexibility of Leporacanthicus and Scobinancistrus, maybe one more then the other as anatomically they are different. This is well recognised with cichlids.
What else is in the tank? There are quite a few variables that could be in play here.
I can't be that helpful, sorry! Although I've had snail outbreaks in the tanks and largely when they do decay the shells take the longest to decay.

[emanuel]

Thanks for your detailed answer

What else is in the tank? There are quite a few variables that could be in play here.

When I opened the topic, I had only one H. subviridis together with a group of 7 L236, 2 L168 and 2 L260, 10 Corydoras sterbai and 3 Apistogramma hongsloi. This remained unchanged, I just added a group of Paracheirodon axelrodi. Furthermore, in the last few weeks the H. subviridis have become 5 and the snails have almost completely disappeared, while the seabed is full of their empty shells.