Dave tells green thing that he is a Pisces too.

After it had devoured his family, Dave asked the alien about its star sign. Turned out he was Pisces too.

ufo = fish on 2 legs

UFO? No it's a fish with legs.

A fish wanting to cross the river, but he cannot for a sign forbids him to cross it.

A fish is sad that this stream doesn't allow fish to enter.

flying fish died cause it flew too long out of water

Jumping the dead shark

The shark died by jumping too high

Flying fish flew for to long and died due to lack of breathing

A blue whale on the beach

Keep her wet lads!