Danio Behaviour?

[fishkeeper35]

i currently have 4 zebra danios in a 15 US gallon tank that has everything it needs to run (filter, heater etc.) and has completed cycling

i have 1 big one, 2 mediums and 1 small one

the small one seems to be getting barely any food even though there is alot still left

added them 6 days ago

the big one waits until the 2 mediums eat then it chases the small one away from the food and finishes the food up until its gone

i also have mashed up the flakes so that they are almost like powder but a little bigger and i mixed 3 types of flakes is this a good diet? ( i plan on getting something else soon)

is this bullying?

also the small one looks pretty lonely and the big one and 2 medium ones are schooling together but the small one is mostly in the corner or near the bottom of the tank

sometimes the small one looks like it doesnt even want the food even if the big one isnt looking

1. what do i do?



2. is this natural?

 

[N0body Of The Goat]

Issues that spring to mind are...
Danios are schooling fish that get quite nasty with each other when kept in small numbers. Increasing your group to 7+ should help. Getting new ones of a similar size to the current small one should help spread any bullying.
Despite their size, these fish are very active and so they need a 90cm or longer tank, with a moderate current (~6-8x water volume turnover per hour) and a temp of ~20C.

Until this last weekend I had Pearl Danios, where I saw that nasty side develope when their numbers dropped below six, but upping them to 10 really helped.