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I have 6 L134s in a 38 gallon tank and all of their tails were biten off. I noticed it the other day and took out the 2 Blue Rams,6 Gold Tetras, and 2 Silver tip tetras. I left the 6 neons who also have heavy fin damage. People at the LFS tell me the plecos are doing the biting to each other, but I find that hard to believe as I plenty of decoration. I suspect the Rams or other tetras I took out. Any ideas?

I would think that they aren't doing it to each other - mostly because Peckoltia species don't really have a mouth to "nip" fins. Bigger Tetras are the most likely candidate in my mind (there are several well-known fin-nipping tetras - they essentially will nip fins of bigger fishes if they get a chance, particularly if they are hungry).

Good news is that with good water quality and some time, they will almost certainly heal up nicely.

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Mats

It does'nt make sense that the tetas chewed up you L134's. Take a closer look at the ragged edges to make sure you don't have a disease problem. Look for bloody or ragged white edges especially if there is no sign of regeneration. I agree with Matt that eh Plecos haven't damaged each other but I suspect you have a problem with a bacterial infection that needs to be determined and treated if you see what I described. A tspn of rock salt/gal and an antibiotic may need to be used. If this is a bacterial infection it can quickly overwhelm them to their demise. You have just recently acquired this group of L134's and just put them in the community tank without observing a 2 week quarantine period have'nt you.?

No, I have had them for over a year and in the same tank. I don't like using salt. I lost 2 plecs in the past using it. The fins don't look diseased, that is why I suspect they were nipped. What about using Blue Meth or Ick treatment?

OK, just work with me a little on this one. I can understand your position on salt. If the tetra did not cause the damage then the plecs have been hassling each other. Try dipping them in 2 cups of tank water with a tablespoon of salt and 40 drops of methylene blue for 2 minutes. You want to see a blue stain on the damaged fin edges and put them back into your tank. Add a hiding place plus one for the 6 plecos. That can work wonders.
I am guessing that since you have had them so long they are starting to set up shop for breeding and they do this sort of thing to each other at this point in their lives, especially the males. If you have a real phobia about salt for what ever reason then just use the methylene blue. The biggest importers of plecos do what I suggested plus deworming but you are not dealing with worms. The salt has a soothing healing effect even as a brief dip. I don't routinely use salt in my tanks either. I only use it on an acute basis. I really think you have plecos fighting(mainly at lights out) and they can do a surprising amount of damage to each other. I hope I'm not coming across as a know it all its just that I have a lot of experience importing fish and saving them so they can be resold and I'm sharing techniques that work for me an others in the industry.
Larry

6 neons who also have heavy fin damage.

Since it's impossible for a pl*co to catch a neon, that leaves disease or bad ass tetras. Do you happen to have UG filtration?

No I don't. I agree, I think it was the tetras too. I have never seen Plecos do that before. I don't think 6 in 38 gallon is too cramped either.

I absolutely agree that it is possible that they are probably doing it to eachother... or poor water quality.

If you've ever at night seen what they do when they are scrapping you would know that they use their odontadotes to scrap and get in a ying in yang type position and can practically shred the caudal and caudal peduncle area on each other in territorial battles, especially the males. *speaking from experience*

Furthermore, the L134, unless it wasn't feeling well wouldn't sit still while any fish did that to it. Like was said above, keep up good water quality and they should heal fine, although.. IMHO, that is too many L134's for that size tank, especially if you have males. Even with heavy plants and driftwood you would have the tendancy to have these issues with them. Do you know what sex they are???

Good luck!

Pureplecs and I gave you the whys and hows that the plecos can do damage you described and ways to resolve it. Believe what you will, must be the tetras even though they aren,t with the plecos any more. Logic and experience does'nt seem to help. Learn the hard way if you will or can. If your lucky the secondary infections that injuries are prone to won't happen and the L134's will stop actng on their instincts and forget that they are plecos. You asked and got the right answers from experienced pleco keepers and want to ignore the obvious correct advice. They're your fish to let nature take it's course. I'd wish you luck too, if that had anything to do with it.

I appreciate your advice, but what is with the attitude? I thought this a friendly forum.

I'm not taking "sides" here, but suggest that if that is the standard 36"x12" footprint 38 gallon tank...it is entirely too small for that many maturing Peckoltia...and all those other things.
How do that many fish comfortably graze in 3 square feet of teritory? They're bangin' in to each other at dinner time!

There's stress in there, regardless of any other opinion or answer.

Kevin

So what is a good size? A 55 or 40 long is only another foot in length. I am hopefully getting a 40L soon, but will it be a cure all?

My apologies for the harsh tone. I have a small red lamp I use to observe nocturnal behavior of the more secretive types. They act much differently at night. Plecos are probaly always best kept in groups with one male to several females and unless it's a very small tank no problems of serious agression arise. If you happen to have a majority of males more space helps but they will still fight with each other. Sexing them is not always all that easy but the fighting behavior is a good clue and some trial and error with some good guessing might help develop a group more interested in spawning than establishing male dominance. Even common bushy nose groups with any extra male(s) can stop regular breeding while the "bulls" try to establish their dominance instead of coaxing the females into their caves. In fact the females establish their own pecking order,too, to see which one will have the spawning rights. If she does spawn then the next in line will take her place.I have had multiple females spawn in quick succession resulting in over a hundred fry instead of 30 or 40.

Hard to tell which are males yet, but there are likely to be a couple in a group of 6. But what is the best size of tank for 6 of them?

The best size for 6?
Anything bigger than what you have.
I'm not being a jerk, I'm suggesting that anything bigger
(more square feet of floor space)will be beneficial.
YOUR tank allows you a little more volume(CUBIC feet), but in the end (at night) they need to roam a little more and graze.
Ideally, you may want to look into a "Breeder" tank. They are shorter, but deeper.

Larry is right about the territorial/behavioral aspect of the fish. 6 might be a perfect # once they've established a pecking order, but they won't do that earnestly until the enter "adolescence". That may be what your experiencing now.

I have 5 full adults getting along quite nicely in a 40 gallon "breeder". It is 36"x18"= 4.5' floor space, called the "footprint". I started with 8 in the same tank and had to remove 3 (one at a time) over the last 2 years. There are 2 males and three females now...and no more disputes.

You may want to break yours up?

I can rattle on sometimes...sorry.
Kevin

Well thank you all for the advice. I guess I will break up the group. Hopefully I end up with 2 groups of breeders.

How are they healing? When mine have scrapped in the past I've dosed the tank with melafix and they healed up good. You've gotten some good advice from some good folks here.. keep us posted!

I've stumbled upon this post a little late, but in reading it, I was reminded of my own experience with my zebra plecs and bitten fins. Don't know if this will be helpful or not, but the more we hear about fish behaviour, the more we can hopefully get a clearer picture of all that goes on.

When I originally bought my first two from the shop, they had been in a tank with Serpae Tetras who were taking random chunks out of their fins, wherever they could grab a bite. Indeed, when the shopkeeper lifted the bit of bogwood one was hiding under to show me the plec, one of the Serpaes seized the opportunity and shot straight down, right through the guys fingers, to grab another bite of the plec's dorsal fin. Right in front of my eyes. I couldn't believe how aggressive it was.

As soon as the plecs were in their own tank they quickly healed up on their own, however, I have breeding adults now and an obvious pecking order in the tank. While this was being sorted out, I would occasionally find a plec with a perfect notch or two bitten out of its tail. Zebras have, what has been described to me as, tiny but sharp little teeth (though whether it's true teeth or some part of their mouth I don't know), and you can clearly see when one has bitten another, which can happen when they are scrapping, which they will do when it comes to territory. Sometimes quite viciously.

So... I don't know if this muddies the water rather than help clear things up... but it seems to me that it could be either, or a combination of both. If your Neon's are getting chewed, it's not likely to be the plecs - I would suspect the other tetras, and some species are a lot nippier than others. So you might reasonably suspect, if you have nippy tetras, they might also be nipping at the plecs, as I have witnessed Serpae tetras doing just that.

However, if space is also an issue, as has already been suggested, the plecs may well be trying to establish and hold on to their chosen spot, especially given they they are either mature or maturing, which could bring about aggression amongst themselves.

You'd really need to spend a lot of time observing your tank to see who the real culprits are. Either way, giving them more space so they can relax, hide and feel less compelled to protect valuable territory will no doubt calm things down somewhat.

Hope this helps.

Thanks to everyone for their input on this topic. It is probably a bit of both, but I took 2 of them out so we will see what happens.