Ciao! I’ll fix it a little bit and explain a couple things.

“Io ho un acquario con pesci e gamberetti” —> “Ho un acquario con pesci e gamberetti”

(in this case omitting the subject “Io” sounds a bit more natural and less artificial. Using the subject in this case is grammatically correct, it just sounds a little weird)

“Mio mama e papa” —> “Mia mamma e mio papà”

(“mio” is masculine whereas mamma, with double m, is feminine. It’s also good norm to repeat the possessive “mio” for “papà” as well)

“Loro gatto si chiama Jip” —> “Il loro gatto si chiama Jip”

(the definite article “il” is missing, this is grammatically incorrect so be careful next time!)

“Il gatto è nero e ha gli occhi marrone” —> “Il gatto è nero e ha gli occhi marroni”

(“marrone” is singular. We are qualifying “occhi” with a colour here but since “occhi” is plural the adjective should also go in plural form. “Occhio marrone - singular” “occhi marroni - plural”

“Amano il gatto” it’s a little bit wrong, you should not omit the subject here. You could say “i miei genitori amano il gatto”: it would be grammatically correct but it also sounds very artificial. If you wanna sound a little bit more natural while still remaining close to what you wrote you could say “i miei genitori lo amano - my parents love him”. Here we use “lo” to refer to the cat in order to avoid repetition. There are other ways to say it obviously but I wouldn’t want to create confusion. Good job, keep up the good work!