Marking shipping bags

[Cinnebuns]

Tomorrow I'm going to be shipping out some female guppies each bred with different males ahead of time. I want to mark the bags to make sure the buyer know which is which eventhough it will be a different number of each. Is it safe to make the outside of a breather bag with a sharpie?  Other choices?

Followup question:  I've never exceeded 4 fish in a bag. Is 5 safe?  Maybe I should do 3 and 2?

Edited September 12, 2022 by Cinnebuns

[AnimalNerd98]

I think writing on the bags with sharpie is fine. I have been to several LFS where they write my name directly on the bags. Alternatively, you could use pre-printed labels or do my hobo version:

1) Write out the labels on a sticky note or small piece of paper

2) Put it on the bag and use packing tape to enclose all the sides of the label on the bag. This will protect it from water. 

The number of fish depends on the volume of water and how much gas (whether it be oxygen or just atmospheric air), in addition to other factors such as shipping time, amount of insulation in the box, temperature, etc. I think 5 should do just fine, but divide them up if it makes you feel a bit safer. I have seen an ASTOUNDING number of fish crammed into a bag at my LFS’ shipments. You could also put it in a piece of Poly-Fil to absorb ammonia if you want to be EXTRA safe.