question about a fish for my cousin?

[Zachary]

i gave my cousin my 10 gallon tank he has 4 mollies 3 standard 1 balloon molly , a single male dwarf blue gourami and a single swordtail as well as a single ghost shrimp a girl rescued a gold fish from being eaten by a human as a dare and gave it to him i don't know what type it is because i couldn't see it clear in the video he sent me but it looked small will that gold fish be ok with thoose fish is it to dirty and will cause an ich or nitrate spike or should it be ok as long as he continually cleans the tank i have him cleaning it every 2 weeks right now and his water is basically as perfect as my 30 gallon tank i replaced the 10 gallon with so once again my question is will this be ok or should the fish go in my tank i have 2 baby parrot cichlids however so i kinda fear putting a small goldfish in the tank for the pure fact they will eat it and yes i know they will need a bigger tank i'm planning on getting a 75 to 100 gallon tank for my dad for Christmas and putting them in there my other fish are a pleco 2 dwarf blue powdered gouramis 3 swordtails and 3 cory cats and a single male betta and i know these fish really aren't all compatable to the real world but believe it or not i am one of the few lucky ones i guess because everyone gets along in my tank and there is no hostility in the tank the two parrot cichlids fight here and there but thats about it please let me know what to do about this goldfish thanks