Throw a sprat to catch a whale.
I’ve never heard the expression “throw a sprat to catch a whale” in my life, but it seems to come out of the 1700s or so: ‘a sprat to catch a mackerel’: meaning and origin – word histories and refers to giving up something of small value in order to gain something of larger value. The German expression seems similar: mit Speck fängt man Mäuse – Wiktionary
The German expression is more about the right incentive than about large and small.
I do not know a good English equivalent, in some circumstances
“Honey catches more flies than vinegar” might fit.
Maybe a literal translation would be better here.
Yes. I can confirm that rodents really like fatty, salty tidbits. So bacon seems quite appropriate here.
An alternative translation could be:
You need to bait the hook to suit the fish.