1.014 g/ml
507g
You won't actually be able to buy just 30g of it. A tin will cost you around £1 - that's 507g. 30g would cost around 15 pence.
That would depend on the species of otter you are asking about. Eurasian otter: 7 - 12 kg, Marine otter: 3 - 5.8 kg, Hairy-nosed otter: 5 - 5.9 kg, Giant Otter: 26 - 32 kg