plecostumus

Question
QUESTION: my last goldfish just died and all that is left is the 7" long plecostumus...I have a warm water tank with some betas and a much smaller plecy, can I put the big one in with the warm water fish ? and what size tank for 3 betas, 1 small plecy and 1 big ..or would it be better off left alone in the tank with no fish ?..plus it is in a window but I know it gets cold at night is this a mistake also ?

ANSWER: Your plecos will both want large tanks, as they will grow to be large fish, at least 14inches in the right tank environment.  I would suggest either rehoming them, or getting a tank of at least 40g in size... and that's on the conservative side!  If you are attached to these fish, and unable to get a large tank, then put them all in the biggest tank.

The rule of thumb for fish is 1 inch of fish per gallon of water.  However, with larger fish(such as the plecos), you'll want to figure it at about 2g per inch, as they will need room to move, lol!

Basically, the bigger the better!

I would wait for a few days, perhaps a week, before combining the tanks, to be sure that whatever killed your goldfish isn't affecting the pleco as well.  Don't want to cross-contaminate the fish tanks and risk illness for the other, healthy fish.

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

QUESTION: any risk of aggression between the 2 pleco's if I combine the tanks ? and the large one has been in cold water all along, any problem with a switch to warm water ?

thanks so much for your help

Answer
While leaving the pleco to see if he's ill, I'd get another aquarium heater and gradually warm the temperature to what it is in the other tank.  If possible, use the same brand of heater.  Find out what the temperature in the colder tank is now, and increase it by two or three degrees a day, to avoid stressing the pleco.  Eventually you should have them at the same temp and make moving him over easier.  If possible(I know with a pleco of that size it may be hard), float him as well in the warmer tank when making the switch.

As for large vs smaller plecos, I've never kept more than one pleco at a time.  I don't imagine they'd be too agressive, just the normal "this is MY spot" tiffs.  To be safe, when you add the larger pleco, be sure to clear an hour or two to just watch the fish, and make sure no agression is displayed.  As well, provide lots of different sized hiding spots, some that are the right size for the smaller one, to give him a safe place to hide if the larger guy wants to be rough.