I have to replace my fish house heater this year and have had my eye on a ventless style of heater instead of the can style I have now. it will be much safer for my little guys in the future as far as burning themselves on it goes. I would like to see some opinions on a ventless VS blue flame heaters or just a normal vented wall heater and also get more info on this subject in general. Thanks in advance

Vented is the only way to go IMHO. Especially with a sleeper, ventless puts out tons of moisture in the air, if you read installation manual on any ventless is always says for supplemental heat only or something on that order. Manual Requires a direct source of combustion/dilution air, in other words, open a window. There is plenty of reasons our State fuel gas code has banned all ventless heaters in MN in any occupancy. With that said, the code does not apply to fish houses.

if you're going to sleep in it, I'd go vented, especially if your kids will be with you. for a day house, ventless is fine. I have a 10,000 btu ventless in my 6X12 and it will heat me out of the house. I have a direct vent in my shack on mille lacs.

I have used a ventless heater in my fishhouse for several years and I have no complaints. Simple, cheap and efficient. The one thing I noticed was the gas line fittings...make sure they don't leak and use a proper fitting sealant. I learned one of my brand new heaters had leaks in the fittings from the factory...that will make the heater stink and you'll know something is wrong.

I would recommend a fan to circulate air as these heaters do create more moisture in the air, it's not a dry heat like the vented heaters.

Definitely use a CO detector.