Not when fully grown your tank is three foot i think??,they are exstremely active,mine are never still for one second,all over the place,there what some people would call aggressive but its just there way...its only between each other like a pecking order,one steps on the others fins n theres a mini scuffle
If I were planning on keeping the pictus catfish, I would aim for 75 gal assuming I wished for the fish to be comfortable. Many of these fish along with Bala sharks become stressed in tanks witrh not enough swimming room. They need this room and often run themselves into the glass on smaller tanks and damage themselves. IMHO 75 gal would be minimum for adult pictus again,,assuming I wished to keep the fish to adult size.
Not meaning to sound funny but why ask the question if you wasn't going to take the advice?.
The above comments in all are quite correct, it makes no difference at times what size a fish gets to in relation to how much swimming space they need to keep them happy.
Pictus are extremely active fish, quite social, so a group comprising of at least 3 would be ideal.
In my opinion 4 foot tank would be fine with larger been better, i don't give gallons in relation to size of tank because a 75g tank could range from 2 foot oddly shaped to 6 foot very narrow.
Basically a rio 180 is a little on the small side but either way i doubt giving advice is going to matter going by the response you made to the suggestions so far
Indeed, it is swimming room that is needed for pictus cats for reasons stated. Small danios,tigerbarbs,swordtails, all do better in larger,longer tanks than they do in smaller tanks. But don't take my word for it, do ask others who have actually kept these fish ,what theyr'e thoughts are.
I have kept pictus catfish for a long time they do need the swimming space mine love their 55 gallon tank they are in now its 4 ft long. Also there is something else to think about that no one has mentioned its that they will eat zebra danios and any other small fish that are shaped the same way such as neons. Trust me I speak from experience here I had several small fish disappear once and have since learned my lesson BTW that pictus was only 3 inches at the time and they were full grown danios.