Yes and cover any place they can get out no matter even if it's just a one inch hole...they can be crafty sometimes. I lost a senegal once and I promised myself I would never lose another like that. Mine is bichir escape proof.
Uwe your right, ive read that in some places Sens are for 5-15$.
Here on the Ice... its a 40$ each and pretty hard too find, a SINGLE guppie is priced for about 10$