Tiger got pink mouth: what's wrong?

The pic below is of one of my 9 inch IT's. He went unstable a few months ago, but rather than go black, he went white.
Never reallly worried, as he eats the most and is very active and does not fletch much, or show signs of itch.
BUT, he is VERY pink around mouth. Also, when he stretches his mouth out his mouth, I can see blood vessels.
The photo is with no flash, but the pink colouration you can see is a very accurate photo capture of the real colour that only i can see in person.

What is wrong with him? Is the pink colour just exentuated becuse he has such a pale white base colour?
I am worried it is Gill flukes? Any related info to share is most welcome.

I have never had a tiger catch illness in 5 years of keeping them.

Knowdafish;2581979; said:

He's been eating too many candy canes!

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Nivce humour...LOL.

but doesn't really help me.. try again

Weylin;2583717; said:

Is he eating ?

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Yep, as i mentioned, he is the greediest of all tigers. can eat atleast 10-15 lance fish in in feed, as well as some prawns. Also, is very active and shows no abnormal signs of heavy breathing

Datnoid 101 has prev mentioned in a post it may be gill flukes. But just hoping someone can confirm now picture is attached