mature

Hi,   I want to buy some Gold Barbs this weekend, but I'm unsure whether I should by the small ones or the larger almost fully grown Gold Barbs.   What size would you recommend? - Is it better to buy mature older fish?   Thanks

Hi   I have recently bought a new tank (Aquanano 40, 55ltr) and am currently running a fishless cycle.  This has been going for over a week now and progress is pretty slow.  My Ammonia reading has been about 4ppm for the last 6 days and doesn't seem to be going down.  I finally have some Nitrite...