Here is the full list of all 15 Fishing Paradiso achievements.
You caught a total of 300 fish.
Your house is now built.
You cleared your first main quest.
You met again with God Fish Martel.
You won the fishing competition.
You collected all the "Signs of Friendship."
You maxed out a friend's Friend Level for the first time.
You became friends with everyone.
You caught all the species of fish.
Your friends tasted all of the restaurant's dishes.
You maxed out all of the fishing abilities.
You caught a total of 1000 fish.
You caught a fish that is at least 100 cm big.
You caught a fish that is at least 1000 cm big.
Hiroki enjoyed the beach chair.