yeah a good rule is usually anything a fish can fit in their mouth they will eat. The kissing gourami when he get larger will eat the zebrafish if he can catch them. If you have a large enough tank just expect to have to replace a couple members of the school every now and then. Another good option would be a school of giant danio's these guys are fast and larger so they will be much harder for the gourami to eat when he reaches adult size.
will the giant danios jump out of the tank...lol...i know it sounds funny to ask but i heard they are jumpers and i have an opening were the filter hangs....so just wondering....its a 35 gallon hexagon ....
well i wouldn't be too worried about it. I've found fish don't usually jump as long as your tank parameters are nice. It's possible that you might lose one but rare. So i think this should be the least of your worries.
Also i just want to note that your gourami will get much too large for a 35 gallon hex. the hex has a really small foot print and this fish can get close to 11 inches.
yeah i have read that and i have also read they may only get to six inches...if i see them getting to large i have a friend with a much bigger tank who is prepared to take them right now they are only 3 inches long.