Lids on tanks????

[ponokareefer]

The LFS I bought my set current set up from didn't recommend a lid because it wouldn't let all of your light through, especially if the glass gets at all dirty. Has anyone seen how high the fish jump over the glass? I have a pretty high canopy(top of the tank cover) and was thinking that they might not be able to get over it, so would hit it and fall back in the tank.