Mounting 72" fixture

[Furnman]

I plan to mount a 72" fixture above a tank where the ceiling joists run parallel to the tank and won't be able to screw into a joist without having the tank 11" from the wall. Is it alright to use toggle bolts or are the average fixtures too heavy?

thanks,
DE

[technomex]

I purchased a Maristar fixture a few years back. They did not recomend that I use toggle bolts on the ceiling due to the weight.