The Terrible Tentacles

I Terribili Tentacoli (The Terrible Tentacles) is an Italian children's book by Cristina Brambilla in the "Misteri A 4 Zampe" series.

Premise
Mystery Inc. is enjoying a relaxing trip to the public aquarium. Suddenly, however, among the names of corals and fish of all colors, check out a monstrous giant octopus that seems very interested in the pool of piranhas... It's up to Scooby to find out what you are looking for!