PlanetCatfish.com

First of all, let me congratulate the people who run this website. My wife and I have learned a ton about our favorite fish species in a very short time.

Now, for the problem: We bought some "talking catfish" and our 5" sailfin pleco turned mean. I put the smaller Hancock's in another tank which had an 8 1/4" sailfin and they are getting along just fine; no aggression at all from the big guy. However, the smaller sailfin in the first tank became so aggressive towards the Anadorous Grypus that I finally took him back to the LFS. So, what made him so aggressive? He left everyone else in the tank alone; the cory, the goby, and the chocolate Raphael we just added.

It is hard to say for sure but there is a good chance that both fishes decided they HAD to have the same hiding spot. Additional caves/hiding places usually helps as well as rearranging what you have to break up the defined territories.
-Shane

I have a 7" Sailfin, i am pritty sure they hate there own kind! mine used to chase the small one all over the tank.

I built him a small cave which the big Sailfin could not get to him, and that stopped it all.

But now there both big enough and have been in the tank a while and they dont fight anymore.

I did read this someware that you have to get a pair very young so they dont fight,not sure how true this is but it seemed correct as that what mine did!

The Sailfin is a very nice fish but a bit on the twitchy-fighty side!

The sailfin's home was under a log. He would chew on grypus, who sleeps buried in the sand, until he woke up and went on "alert", then would dive back under his log. Grypus would then dig back under the sand.