I started my Steam version of Fishing planet 4 years ago and have spent around 4000 hours so far on it! I’m now at level 80 with 12 million credits. As you progress further, you’ll find that the higher level lakes can potentially give very much higher rewards per fish, eg Bolivia, Catfish can net as much as 20,000 credits. Coins are mainly from winning competitions. Look for the sponsored competitions as they have much bigger payouts for winning, eg 20 or 100 coins instead of a measly 10. Hope that helps and thanks for your comment.