For adults and juveniles -- no lids. Makes it easy to do quick water checks/changes as well as introduce prey items or remove uneaten ones.
For the times I want to move a tub to a work area I use a piece of acrylic that sets on top so the snakes are secure until I get where I am going.
I'm less picky for hatchlings but still prefer lidless.
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Currently keeping:
6.10 Gonyosoma oxycephalum (Javan, mixed colors)
0.0.4 Rhynchophis boulengeri
1.1 Philodryas baroni
1.1 Lampropeltis triangulum multistriata
0.0.1 Rhamphiophis rubropunctatus
0.0.2 Morelia viridis (Aru & Merauke locale types)
1.0 Rhodesian Ridgeback