My 2 cents worth
Your water looks like pea soup, so IMO a min of 50% per week WC.
It looks a nice fish, much like my Bob, spotted more than blotted
I also think that 24 inch in 6 months is OTT a bit, feed mine 2-3 times a day on muscles, cockles, prawn and high protein pellets in a water temp of 75, and when i got him about 6 weeks ago he was about 2 inch and now he is 7 inch and as happy as larry in his 150g (UK)...dont ask i dont know larry
You should defo get a bigger tank as soon as you can , mine will be going into a 500g (UK) then a 1300g (UK) tank in the next 2 years.
Another thing about folk posting on here, please try to be a bit nicer to folk instead of diving in with abuse before asking a Question. It just p***ss folk off. Be better to either ask then advice on what to do, or is it just me getting fed up of these web forums
All the best with the cat mate, but if you ever think you will not cope get rid asap.....then regrett it.
Oh yes, if he dont take pellet easy i stuff my cockles etc with the pellets.