Safe frozen tilapia for garters?

[FlagonFly]

We just picked up a ribbon garter from Repticon. No clue on age but it's definitely not a baby, almost 2ft long and very skinny of course. The breeder suggested feeding frozen tilapia bits.

However I read in a post here to watch out for Sodium Tripolyphosphate in the ingredients. We have fed it twice now with some Market Pantry (Target store) frozen tilapia. The ingredients simply say "farm raised tilapia" and also that it's a product from China, but nowhere do I see anything else listed besides sodium daily percentage info and such. Is this safe to feed and can I assume that if I don't see that on the label anywhere that it's not present?

[infernalis]

Law requires that it is listed on the label.

However, whole guppies is a better choice.

I feed my Thamnophis (garters) mostly pinkie mice.

Night Crawlers (jumbo worms) are also a favourite of garter snakes.