Hello all. I'm a newbie here and a newbie at keeping fish. My brother's roommates moved out of the house they were renting and left a 20 gal. I volunteered to take them and got them about a month ago.

They are a Tiger Oscar (I think albino), a Red Pacu and a Plecostomus. The Pacu is becoming more and more aggressive every day and I am trying to give it away. I'm hoping someone will respond to my ad on craigslist.

I know a 20 gal tank is too small for these fish as adults. Right now they are quite small. The Oscar is about 3 inches long and the Pacu is about 4 inches. The Pacu seems to be growing rapidly and I hope I won't have to keep it much longer.

I really enjoy watching the Oscar. The other day I was feeding them and he jumped about 3 inches out of the water and bit my fingernail. What a surprise. He's a funny little thing.

I am enjoying reading about them and how to take care of them and their tank. I know I'll have to get a larger tank at some point.

One question for now...is it okay to keep my Oscar alone in the tank with the Plecostomus after the Pacu is gone? I don't think I want to bring in another fish if I don't have to.

hello and welcome to ofl, you will lern so much on this site.

first off your right your tank is really small for those fish if you have a common pleco they can get up to two feet and the oscar over a foot. So before the oscar and pleco get to big you need to upgrade a oscar needs a 55 gallon and i forgot what a big pleco needs. And you dont need to add any fish because you simply dont have enough room for any of those fish (if i am right). But a upgrade as soon as posible would be good, hope to see you around and again welcome to the site.

Hola,

First off, You came to the right place for advice on your new oscar..so good on you for seeking advice. I started out with an oscar in a 20 gallon as well before finding this site and I'm very glad i did.

As for your fish---good thing you're doing something about the pacu already. To me that would have been step 1.

Anyways, it really depends on what your plans are, are you planning on keeping both? If so, you are going to need 90 gallons for both of those fish. The 'common pleco', (as several types of plecs are referred to as), are the most type most 'commonly' found in your average pet store, so I'm going to assume that is what you have. They routinely can grow 12-15 inches, and more, and with a healthy environment its not uncommon for them to do so. I had a common plec for about 10 months and he grew from 3 inches to 10 in that time span and was still growing. Plecos and oscars do get on just fine together, btw, but they are very large and very messy fish. Smaller tanks are not just too small from a size standpoint, the waste they will produce will overwhelm any attempts at maintaining any semblance of good water quality. This will inevitably lead to poisoning, any number of diseases, stunted growth, poor quality of life, and finally a very short life span. This is not even mentioning the behavioral ill-effects such as aggression, lethargy, etc.

Here is a sample of a fully grown pleco for reference (though most in captivity will not reach this massive size, many are not far off);



Here is a captive pleco in a 55 gallon. As you can see even by himself with virtually NO decor he can barely turn around, and was later rehoused:




The oscar will also grow very, very quickly, I would venture to say most captive oscars grow to a fully mature 12 inches on average (about 15 in the wild), and some can weigh in excess of 2 lbs.

If you were not looking for that type of expenditure with your fish I would probably recommend rehoming your pleco in the same manner you are with your pacu, and at the minimum obtain a 55 gallon tank for the oscar. They can be housed in 55 by themselves, but flourish best in about a 75 gallon. Again, 55 at the minimum for one. I would stress that you need to do so very soon, as soon as is possible. You can find all sizes of tanks and stands etc. fairly cheaply on craigslist as opposed to standard pet stores.

A few things;

1. what type and size filter is on there now?

2. Do you know if your brother's roommate 'cycled' (see helpful articles section) the tank and conditioned the water (removed chlorine)? I would think if he chose to house those types of fish in a 20 gallon he most likely wasn't too experienced himself so we need to start there. Again, If you are not sure about terms and such read the FAQ section OFL has provided as well as the helpful articles section at the top of the page. That is crucial to do as a first step.


If that size tank etc/expenditure etc. wasn't in your plans/not doable in the near future I would strongly recommend rehoming all of them as soon as possible, as they will most likely have a very short life span in a 20 gallon, even with very good maintenance. If you can and are interested in keeping on with it, great. We can help getting you off and running. You'll really love the oscar. They're very, very unique and a lot of fun.

joymarv wrote:


Ive got my oscar and pleco together.. they get along so-so. they fight over territories, but nothing too serious. you want to make sure that the pleco cant get eaten by your oscar. and expect fighting to get worse in a 20 gallon tank, and quickly.

I started out same as you, except with 3 pacu. I took them to a pet store once I saw how big they were going to get. I would suggest getting it to a pet store. Craigslist is great for tanks. I got a 55 gallon recently. Now the oscar and the pleco are better tankmates.

Good luck and welcome!

I am a new oscar owner as well i found this site befor i went and got my tiger oscar and this site helps ALOT every one here is realy nice

you should post a video or pics of your tank i want to see them

Hey there and Welcome!

These guys have you covered on what you need to do!

hello and welcome.
Johhny has spoken for the pleco loving community here over on ofl.

Given enough room plecos and oscars can get along great.
I got 2 oscars and 2 pleco's in my 180Gl and they don't ever bother eachother.
I think it's mainly because the oscars eat different food, so they don't see the plecos as a threat.

Red belly pacu has to be moved quickly and will need an outdoor pond to thrive for they get very big very fast.
Here is a vid of some full grown pacu and the tank they are in is over 40 feet big.


NOTE:My one year old(!!!) daughter saying"Meerval!"(w.i. Catfish) when she notives the red tail catfish in
between the pacus at 19 secs into the vid!!!! My best moment as a dad so far!

here's the tank itself, MASSIVE, but needed for pacu and RTC.

Welcome to OFL

and good luck in your hunt for a bigger tank. Whatever tank you get you will need filters rated for a tank twice as big. cannisters are best in my opinion

dwencl wrote:


My plec and oscar were ok together. They kinda picked 'sides' of the tank, and hung out there. Really the only aggressive behavior was when the pleco would come out during the day and forage over on the oscars side. The oscar would eyeball him and occasionally give him a nip on the fin or body, and the pleco would just kinda ward him off by extending his fins and swimming at him, and then head on back over to his 'side.' At night the oscar would let him do his thing, and they seemed to have formed a general truce. Still, I would not have introduced the plec if he was not of comparable size unless both were very young.

Alot of the time the oscar would seemingly observe the plec, almost out of curiosity...he would get close and watch him, and occasionally rub up against him. I dont know if this was another means of 'observing' him, trying to intimidate him, or some sort of misguided mating behavior, but it was kinda funny to watch. The pleco was like, 'Forget it, buddy. I don't swing that way."

johnnyphoenix wrote:


LOL, yeah that sounds like my two.. most of the time they are on their respective sides. Fluffy seems to have staked the entire tank as his, so hes busy patroling for intruders. Hes loaned out the space under the filter for the pleco, but still goes up there occasionally to remind him that the space is on 'loan.'