My Pleco q.q

Question
QUESTION: Hi, I have a new but cycled 20 gallon tank that I recently upgraded from a 10, it has 4 australian rainbows and 4 cories. I took all the used and cycled stuff from my 10 gallon and put it in the 20. I rinsed it with the old tank water and put half old tank water and half fresh treated water. When I had the new tank set up with everything, a plethera of live plants included, I noticed my 8 in pleco from my 45 gallon tank was being attacked by the lone jack dempsey he tanked with. So I moved him to the twenty gallon, everything was great for the first week, and I haven't seen any Behavioral changes but the pleco is getting this little cap at the underbelly where the tail starts (his anus) I had another pleco who did this, then bloated up and died and I never knew what happened. I keep my levels as stable as I possibly can and I have a 50 gallon filter on the tank. I don't want my big fella to die, can you help?

ANSWER: Hi Natalie,
  I have noticed over the years that large plecos often do not "move" well.  I strongly suggest you put him back in the original tank and provide more protection for him, i.e., add some large chunks of wood for him to hide around (plecos love hiding on the underside of pieces of
wood).

-- Ron
   rcoleman@cichlidresearch.com
   Cichlid Research Home Page <http://cichlidresearch.com>


---------- FOLLOW-UP ----------

QUESTION: Even though I did the bag floating deal? For like 50 mins he floated and I slowly introduced the new water

Answer
Hi Natalie,
  Yes, this problem occurs even if you introduce him slowly.  I suspect the problem has to do with diet.  Plecostomus have very specialized diets, basically they eat a mixture of wood and the plant/algae cells growing on the wood.  They have a very specialized gut fauna to deal with this.  I suspect that when you move them, this disrupts their guts and they often die.  I have noticed this several times with larger plecostomus.  I haven't proved this connection for sure yet, but I have noticed it several times so it is something to think about.  

-- Ron
  rcoleman@cichlidresearch.com
  Cichlid Research Home Page <http://cichlidresearch.com>