I would use a size 18 french catheter, which you can get from your vet, but you could also use a piece of aquarium air line if you melt the end of the tube to remove the sharp edge. You will also need a 60 ml catheter tip syringe. That you can get from a vet or Tractor Supply.I'll go tomorrow and get supplies. what size tubing do I need and where can I find it? The vet did give him fluids twice, I've been spending a lot on my rooster but he is worth it!