My Pleco The Killer

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FroFro

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I recently moved across the country and I just set up a very nice forty gallon aquarium. I'm still waiting for the new tank to cycle and establish itself before SLOWLY adding fish one at a time to it.
 
Now here is the story. Before moving I donated my fish to a high end and family owned tropical fish store and kept my pleco by sending him over night mail.
 
I've had this pleco for about 3 years now. He's an Albino Bristlenose Plecostamus and has always been indifferent to other fish in the aquarium even the other bottom feeders like my albino cory cats before I had to give them away. I've always had a love for small species pleco and I attempted to adopt over 4 different species over a period of time. None grew larger than 5-7 inches according to the information I looked up on them. Non aggressive and I made sure to get pleco's around the same size or slightly smaller to avoid any "bullying" should it happen, even though my pleco is pretty chill. All four died overnight after introducing them to the main tank once they passed quarantine. I couldn't fathom how they kept dying when they were healthy and disease free and none of my other fish showed signs of illness or distress. My water parameters were normal, tank clean, strange!
 
Until I found him gnawing on the empty face hole of my brand new rubber-lipped pleco. The other fish I had at the time consisted of the 3 cory catfish, 2 Silver and 1 Koi angelfish (all male so they weren't mated and aggressive) and my pleco in a thirty gallon tank. The few times I would discover a dead or sick fish in my tank my pleco was usually no where to be seen (hiding in his favorite hollow rock most of the time).
 
So tell me, has anyone ever had an issue like this before? Any theories to why he kills other pleco's even when there isn't competition for food or mates or anything? I'd really like to have another small pleco species and have thought about buying another young albino bristlenose but I'm afraid he'll go on another murder spree.
 
Plecos will happily consume any dead tank mates.
 
I have a full grown male and female in a 6 foot tank with Tetras and Clown Loaches, and even the Clown loaches and the female pleco know to stay away from the male especially at feeding time, The only time he tolerates the female near him is when shes laying eggs in his cave, The clown loaches do not go near his cave anymore.
 
yes.
 
I had two ancistrus catfish (BN's) both bought together from the same place. I was hoping for a male and a female but what I got was two males. They lived happily together for about 3 or 4 years. They occupied opposite ends of my 4ft tank. They had different temprements though. One was laid back and no trouble - he just wanted to sleep under his lump of wood. He was happy to share it with my cories and he only ventured out when he was hungry. He's very shy - the slightest noise or movement and he darts back under his wood.
 
The other was a bit destructive. I'd get up in a morning to find he'd re-arranged my tank in the night. He'd bulldoze my sand into piles and uproot plants etc.
 
One Sunday I was cooking my meal when I heard some bangs from the tank so I came into the living room to see what was going on. All my fish were trying to get out of the tank. Sand was flying everywhere. When I got closer I saw both my BN's in the middle of the tank smacking hell out of each other. They were using their cheek spines to batter each other about the head.
 
Now, my Dad has also kept fish all my lifetime -so well over 40 years so I rang him in a panic. He told me I'd have to seperate them if it was that bad I said "it is Dad they're trying to kill each other". He set off from his house with an empty ice cream tub and by the time he got here the destructive plec was in a bucket of water. He took him in for the night for me and the following day he went to my lfs to be re-homed.
 
Two adult male plecs will fight once they hit maturity (as your has done) 
 
I had the same with two Leopard Sailfins I'd had since they were less than half an inch long.  One day they just decided that enough was enough and they'd not tolerate each other any longer (before that they'd been inseparable).  They started circling and fighting just like Akasha said with hers.
 
Both were rehomed to friends of mine who had no other plecos and they have since settled down.  Since then I stick to my own rule of one pleco per tank.
 
To be clear, male BN plecos are not 'aggressive', but they are 'territorial' towards conspecific fish.  They will happy cohabitate with other fish and are therefore fine for community tanks.  It is the introduction of another BN that will cause trouble.  Adding a female that the male can spawn with, and you'll be fine.  But add a male... and bad things will eventually happen.  
 
 
Male BN plecos, once sexually mature, will look to create a territory for themselves.  In the wild, if a dominant male comes across a less dominant male, the less dominant will usually move off to new territory without incident.  But, when there is no where to run to, or if they are evenly matched, then a fight will ensue.  In the case of males in the aquarium, there's no where for the other pleco to go.  So, you will always end up with a fight, and usually at least one dead pleco.
 
 
To be clear, male BN plecos are not 'aggressive', but they are 'territorial' towards conspecific fish
 Explain that to my male BN next time a Clown Loach goes near his cave. He actually chases them away.
 
Well, then yours is a bit more territorial against a slightly wider scope.  I've never kept clown loaches with a BN pleco.  
 
Hi I've got dwarf B.Ns there only 1.5 inches at the moment but I've got four in a tank not sure what sex they are can anyone shed light on how to sex them ?
 
Mjsgonefishing said:
Hi I've got dwarf B.Ns there only 1.5 inches at the moment but I've got four in a tank not sure what sex they are can anyone shed light on how to sex them ?
 
Yes the males will grow bushy growths on their nose and the females won't - they will remain mostly smoothed nosed.
 
I'll see if I can find a photo of my male BN so you can see what the 'bristles' look like :)
here you go
 
Male BN
 
040_zps5f3c3f85.jpg
 
Thank you for your help , it's good to know just in case I have to separate them
 
if you have more than one male they will have to be seperated at some point but if they are babies right now you probably have about 2 years to work something out. I think mine were both between 2 and 3 years old when the trouble broke out.
 
I have no idea if pleco's 'pair off' so you may have to watch for any bullying if you get a male and female that breed - they may pick on the others. This is purely a guess though as I have no experience of a female. Maybe someone will be along later to expand on that a bit more :)
 
I have a female and a male pleco in a 30 gallon tank with no problems the only other bottom feeding fish are two small Gobys.
 

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