BN Plecos Fighting (maybe mating?)

[Stef]

Hi Everyone.  As I was feeding some frozen brine shrimp today in my 10 gal tank (it's a Dennerle Scaper's tank so it's short but deep), two of my 3 young BN plecos went into "roid rage" and were mashing faces and thrashing at each other under the sponge filter. The fight lasted maybe 2 minutes and I tried to separate them using the end of a net to break them up. They went into their caves but one came right back out and sought out the other and started fighting again. 

I bought these three "babies" on Sept 1st 2021 and they were all about 1-1/2 inches long (too cute).  Two have gotten quite big already (the two that are fighting). Only one of the two bigger ones is getting his bristles which look more like stubble around the mouth area (not so much on the head yet).  The third is still fairly small.  All are healthy looking and have nice bellies. They get a variety of foods like green beans, flake, wafers, zucchini, blood worms and occasional Repashy morning wood.  At the time I bought them, I was battling a major algae problem (too much light) in this tank and thought 3 BN's would take care of things plus it was a 3 for $ sale at the lfs so I said "sure I'll take 3".  There is some drift wood in the tank and each has a cave (1 coconut hut, 1 ceramic cave/tube, and 1 natural rock cave I built by tenting two seriyu stones).  I know 10 gals is too small and want to get a larger tank.  Life is getting in the way of my MTS plans and I haven't been able to get my dream tank.  So I thought either 1) remove one of the larger BNs to my 9 gal Fluval Flex which only has 1 molly and its 10 week old single fry), or 2) go out and buy an emergency 20 gal long and set it up to break them up. I don't yet have a stand or sturdy dresser for a 20 gal, tho could make do with a bakers rack/shelving unit. All my other tanks are 6 gal cubes or a 5 gal.  Is there a chance I'm mistaking their fights for mating?  If not mating, can they kill each other if I don't break them up?  I'm not interested in breeding.  I'm really more into small nano betta tanks but willing to make a move to a larger tank.  I really like the BNs and they're a blast to feed and watch their behavior.  They can sniff out food like nothing I've seen.  I keep up on water changes as this tank gets quite poopy.  Other occupants are a mean old betta, 3 panda corys, 2 amano shrimp and 2 nerite snails. 

Appreciate your thoughts on how best to split up the BNs?

[Guppysnail]

Being that young it sounds much like establishing territory and dominance.  If they are male when the get older than can injure one another severely enough to cause mortality. For keeping more than one pleco depth is not nearly as important as length and larger available floor space with separate areas so they can each claim a portion of the tank with sight breaks and sort of segregated area. Even a normal 10 g foot print is going to be too small very quickly. I have 2 born to me mid august in a 10g. They are starting To squabble but are being rehomed with all their siblings next Saturday. 
Your first thought of placing the largest in the Molly tank is a good one. If that does not take the pressure down buying you time to make appropriate setups you choose move the smallest to one of the other tanks. Best of luck great observation skills. 

[Stef]

Thanks @Guppysnail, your experience is invaluable.  I know the 9 gal is not ideal, but its low stocked, has more driftwood and lots of hides...and no other plecos 😀  This is going to sound dumb, but with regard to catching the pleco, does their armor get caught in the net material?  Their skin/armor looks kind of spikey and rough. I'm thinking of trying to catch him at lights out and scoop him out while stuck to his inner coconut hut to avoid the net altogether.

This first two pics are when I first got them in Sept last year (compare their size to the cory).  The last two pics were today post fight of the two larger ones.  Are those sucker marks on the back/head area??  You can also see the bristles developing on the one in the background. The one on the filter has no bristles that I can see. 

[Guppysnail]

My eyes are not good enough to distinguish bristles or marks I’m sorry but they are good enough to say those are cuties. I don’t have issues with them getting caught in nets I use fine mesh nets or coop nets. If they do stay calm and gently untangle them under water. The coconut scoop is a great idea. I use mines favorite green beans and scoop green bean and fish into the net 🤣Take care they are powerful and can and will jump out of the net..I learned that the hard way 😝 keep your hand over the top. 

[anewbie]

Those look like females if mature. Females normally do not fight but males will build a cave and defend it. However a 10 gallon is way too small for bn pleco and that might be a real issue.

[gardenman]

Two and three are bad numbers with fish that are somewhat territorial. It's pretty easy for the "I want to be king!" pleco to find and bully the others. If you up the numbers, aggression seems to lessen as there are just too many fish to bully. I have six young adult Super Red plecos in my ten gallon tank along with God only knows how many pleco fry from a recent spawn. There's very little aggression in that tank. (The biggest female is the most aggressive pleco who forces her way into a young male's cave who isn't sure he's ready to be a pleco daddy. That's not how pleco aggression typically works, but whatever. Instead of trapping her in the cave he typically swims away only to her come out and wonder where he went.) I really don't see any aggression from my Super Reds. There are no torn fins, no damage, just general harmony.

[Stef]

Interesting @gardenman, thanks for sharing.  I managed to catch the one I think is either young male or adult female (the only one with emerging bristles).  He's acclimating in a bag in the 9 gal.  I measured him while in the bag and he's exactly 3" nose to tail.  Hopefully peace returns to the 10 gal with the remaining two plecos. Fingers crossed.  And now I have to up my game in looking for a bigger tank and stand to fit in my living room 🏃‍♀️

[lefty o]

as for moving with a net, yes they will sort of get into the net like velcro. though if you place it back in the water and gently shake it, they come right out.