TECHNIQUE & EXECUTION: Everything looks very well blended, love the colors you choose and how you made the fish color pop. This makes the viewer attract even with the THUMB of your work.
Some changes i would make: She looks a bit green with all the blue around here, i would open this in PS and would go to image, adjust, image tone, select blue, keep illumination and make it more blended with the overall composition. For the hair a smaller brush to add detailed strands would make it more realistic too, maybe a white brush. The same for the fur on her tail.
Love how the glass explodes but because of that there should be some smaller glass parts near her face and hair like the ones behind her. Maybe also instead of add a color on top of the fish, make it into overlay with a new layer in PS.
Her chain also needs a but orange glow to fit the composition. Also the hair near the fish needs orange strands or a overlay color of the same.
ORIGINALITY: I have seen many cats around DA, this is the first time i see a fish poping out of the glass sphere like that, very good decision
Her eyes are perfect for the cat character, also the tail you added and the ears repainted with a realistic fur in it, love them.
Hope my suggestions help you in your journey & remember critics are here to make our mistakes into masterpieces, not to make you feel bad or be mean
And for the watchers, remember to be original, and look but don´t touch. Don´t steal, don´t claim as your own and for the love of god, don´t sell images that don´t belong to you