just lost one of my oscars. had a pair and for some reason one of them decided that the grass looked greener on the other side and jumped right out of the tank. sadly no one was home. the remaining oscar is now alone. what effect will this loss have on him and is it wise to introduce another oscar but smaller in size

How big is your tank, and how big is the remaining oscar?
Sorry about you loss, btw.
Did you check you water stats to rule out your oscar jumping out of the tank to escape bad water quality?

i had a feeling the water quality had something to do with it. with final exams around d corner i must admit that i have neglected my fish. i was thinking of introducing another oscar. the 1 i have presently is around 9inches and the newbie is a 4inch tiger. what do u think.

Your remaining Oscar will be perfectly okay. I would suggest that you either put a lid on your tank, or secure it properly. Oscars are very capable of lifting the lid on a tank up.

Sorry to hear about your loss, its gutting when you lose a fish

Oscars do sometimes jump for no obvious reason. Oscars are very inquisitive and if they see something they want to check out they might end up out of the tank, I have seen mine go mad for a fly on the outside so i can see how they could follow one and then go for it and end up on the floor. Maybe it got spooked and jumped, mine have gone mad sometimes when i have been moving decor around. For this reason its best to have cover glass and a lid on top of that

Check out some of the other threads on adding another oscar. Make sure your water quality is good before getting another oscar.