ABANDONED. Childrens/YA/ - Book about a boy on an adventure to find a shark-hybrid creature

[Alo]

I read this book around 2005, I think it is by a British author.

A young boy gets sent to live with his aunts because he is very sad and lonely and doesn't speak much. His aunts cook up a plan to make him happy by making up this story about a creature who is part shark, part octopus and I think part tiger. It has a Scottish man going by the name of Captain something and he wears a kilt. The book is quite long for a children's novel and it does have some illustrations in it. I think one of the aunts was called Dede? And she was in a relationship with the Captain. I've been throwing all sorts of keywords at Google and I'm coming up blank. I think the aunts lived in a hotel of sorts. The cover was possibly blue with a shiny hybrid shark on the cover. I'm not sure why I can't find this book because it wasn't too obscure back in the day. The author was prolific in writing very fun, quirky and sometimes sad books. I remember he wrote another one about a trolley cart.

The title was something like The Mighty Sharkzilla, but it wouldn't surprise me if that's completely wrong.

[Tab]

Maybe, Attack Of The Tentacled Terror by Susan Gates?

There is a description at Fantastic Fiction
https://www.fantasticfiction.com/g/su...

Or, one of her other books: "Sea Hags, Suckers and Cobra Sharks."
Here is the Fantastic Fiction link
https://www.fantasticfiction.com/g/su...

Do you remember the time period/location the story takes place?

[Alo]

Unfortunately, it's not that book. I'm pretty certain it's a male author. Also, I think it was present day.

[Peter]

His aunts cook up a plan to make him happy by making up this story about a creature who is part shark, part octopus and I think part tiger.

I'm trying to figure out how that would work. "When a zoo and an aquarium love each other..."

[Ayshe]

Alo wrote: "...I'm not sure why I can't find this book because it wasn't too obscure back in the day. ..."
British books often are difficult to find, at least that's my impression.

Mighty Fizz Chilla by Philip Ridley? The trolley book is probably Zip's Appollo (that was the clue that helped me find it).

[Lobstergirl, au gratin]

Alo, are you still looking for this or did you find it?

[Kris]

No response, moving to Abandoned folder.

Alo (OP) was last active on the site in October 2020.