I have a red tiger oscar who likes to jump out whenever I feed it. This is a problem, twice my oscar jumped out on to the floor and almost died. When this happens he is very slippery and always slides out of my hands.
I have a red and an albino about 15 cm long, with a jack dempsey and two managuenses. The red oscar is the dominant one. The albino and the jack are constantly fighting for dominance, but my oscars are the most beautiful fish I have ever owned, and I would recommend them to whoever could afford to feed and house them.
I have 3 huge Oscars (VERY messy fish) and an algae eater in a 280 L tank with one Magnum 350 Bio. It took several months to get well established, but now works great. The carbon is left in until vac and water changes, when I use the polishing filter for a few hours or days to clear up the water. I keep two polishing cartridges going by cleaning them in bleach solution in a zip lock baggie and rinsing well, air drying and a "sniff test" for chlorine before use. I use a siphon now instead of vacuuming into the canister, which will clog rapidly that way. This also accomplishes the water change. Works great. The bio wheels do their job and nitrate/nitrite are very well controlled with water changes of about 25% every other week. Haven't used other systems, but am very happy with this one. I get compliments on the clarity of the tank and the Oscars have bred 3 times, so it's working.
I came home day before yesterday and told my husband that I was going to get another Oscar. We had one several years ago that we were very attached to. When he passed, it broke our hearts. He would eat out of your hand, or rather try to eat your hand if it stayed in there too long! He would hit the top of the aquarium lid when he wanted your attention. He would follow you around the room as you moved. When I or my husband would come home, our two Boston Terriers would start barking and running around, and then our Oscar would start fanning himself wildly and swimming from one end of the tank to the other. Of course, we'd have to greet the Oscar just like we'd greet the dogs. Our Oscar used to tease one of my Boston Terriers! The Oscar would jitter and hit the side of the tank or knock on the lid and it would drive my dog crazy!!! My dog in turn would get up to the tank and mouth the outside of the tank and growl and snarl and spit all over the outside of the tank. The Oscar loved it! He never backed off! He would just continue terrorizing my dog until I'd go and get the dog away from him. I'd shame the Oscar and he would just act so proud of himself. This was at least a once-a-day ritual with the two of them. I've had other fish, but this is the only one that's been a pet. They're actually almost like a child and you can get just that attached to them!!! Oscar's are worth every bit of the effort you put into them!
I have a baby tiger oscar in a 29g tank with a jack dempsey, a red devil, a firemouth, and a convict. The oscar is the smallest fish in the tank right now, but is the most dominant by far!!! Oscars are really cool fish and it's really fun to watch them eat.
I currently keep two 30 cm oscars in a large tank, together with a large leopard pleco and five tinfoil barbs. Oscars tend to be aggressive towards new fish, but are docile with familiar tank mates, i.e., ones they see every day. I have had them attack and kill a catfish that had been their tankmate for months, but was largely nocturnal. By the way, this catfish was a lot bigger than would fit in their mouths and they didn't attempt to eat it. While they are very tolerant of water chemistry, you must keep an eye on water quality - oscars are filthy feeders and I carry out 50% water changes weekly to keep the nitrate levels low. My oscars live in a planted tank. I use tough plants with good roots, planted in gravel and secured by large pebbles. The cover gives them the opportunity to get out of each other's sight and I feel is beneficial to their cohabitation, however they do like to rearrange the tank to suit their preference. If your fish do this, go with it - they will only move plants etc again if they don't like where you put them! I do sometimes rearrange their tank a little if they are getting aggressive towards each other - putting it right again sorts out their differences. Oscars are prone to hole in the head disease so it is important not to let water quality drop. Feeder goldfish seem to be the main culprit for introducing disease to oscars. I recommend breeding your own feeder fish as a treat for your oscars, but use Cichlid Gold or DoraMin as their main food. The tinfoils clean up any scraps from the gravel.