I started out, as most do, writing on tubs and tanks. But eventually, as happens to most things around here, I found a fun and creative alternative; cards in the image of the snake! I've used them for meal dates, names, notes, just about anything.

Each card is approx. 3 inches wide by four inches tall. 
They are printed on card-stock and laminated, with velcro to attach to plastic or glass, or use your own adhesive if you like. 
Use with wet erase markers such as Vis-A-Vis

Bundles of three are $5.00
Indivisuals are $2.00