I couldn't find the article I found yesterday about the difference between the two. What I do remember is that the bars of the C. Monoculus are wider than the C. Ocellaris. And also, from the same article, the bars disappear on the C. Ocellaris when they are larger, around 4lbs, but the monoculus keep the bars. I wanted to give credit to that article I found, but I couldn't locate it. All I did is search the words - difference ocellaris monoculus without any quotes, and I found that website, but now it is not showing or couldn't recognize it. It also mentioned that it is difficult to differentiate until it gets to around 6-8 inches. I'll keep looking for the article. At the current picture, I believe the fish in the picture above are C. Ocellaris. But I am not a taxonomist (disclaimer).