I would advise against a mandarin or psychedelic mandarin. They need lots of space to hunt copepods and such and rarely eat non-live food. They are absolutely magnificent animals, but they'd be really unhappy in your 35g. They are recommended in no less than 100gal.
They get to be about 4" i think. they eat mostly live worms, copepods, and live brine. They sometimes eat frozen food, but don't count on it. They are the most non-aggressive, loveable, active fish I have ever seen. Notice my avatar. My system is 55 gal
, but I have tons of fauna and pods
and such, and mine luckily does take frozen. I'm upgrading to 120 gallons though. I don't want to take the chance of a 20 year life span narrowed to 1 year, ya know?
So, in short, my advice is the followingf:
Get a bigger tank, then get a mandarin.