كرسبي is understood and used by many Arabic speakers. Yet, it has an equivalent adjective in Arabic: مُقَرمِش / مُقَرمِشَة . As for the word سوط you've used, it doesn't make sense. May be you mean medium-fried? مقلية وسط؟ One more thing, when you speak about things in general, plural nouns are used. So you need to replace سمكة which is a singular feminine noun with سمك which is a plural noun. By default, the adjectives change and the sentence should be أفضل السمك المقلي As for the second part, you need to start with لانه since you have a why question ; لماذا تحبه A grammatically correct sentence that makes sense should be طعامي المفضل هو السمك المقلي لأنه مقرمش ولذيذ.

Crispy= مقرمش (moqarmash) I didn't get the word سوط, but I guess you meant deep-fried, in Arabic we don't have a word to specify this kind of cooking (maybe I'm wrong). Well done 👍🏾 Keep practicing Arabic. Don't hesitate to message if you have any questions about the correction, or the Arabic language in general.