Gold fish Tips

Question
hi,

i am having a 7Gln tank, having 2 gold fish, and 2 moles. Now my Problem is, How much do i need to feed them(dry Worm) per day. as the aquarium is small in size, can I fit a small filter in that, if not then how can i clean that.

And i am confuse that whether to put Garvel or sand on the bottom, Please suggest.

Regards,

Partha

Answer
I am not familiar with moles, did you possibly mean mollies?
You don't want to feed them more than they will eat in a minute.  Plus you don't want to feed them more than three times a day.  They will eat more than that, but if you feed them more than that your tank will get dirty fast.
I am a little confused.  Do you have a filter in the tank now?  What kind is your tank?  Is it rectangle or tall?
You could put gravel or sand, but I would suggest aquarium rock.  Sand tends to make your water very cloudy.  
Please let me know if I can help you better by suppling me with the additional information I asked for.
Good luck!