Well I guess I am the odd person out in this thread, as I find PICO sized tanks to be no harder to keep than larger tanks. Yes you can get lots of money tied up in them just like a larger gallonage setup but PICO size is unique and yes, you can keep a fish in them if you choose your fish wisely...Neon Gobys and Rainfordi Goby make excellent fish for such sized tanks....I have large tanks but still find myself setting up PICO tanks all the time....They need not be expensive per se, for just a decent hob type filter, and light, what costs is what you put in them in the line of livestock, and there is no way a fully stocked pico is going to cost anything near what it would be to stock say a 29 or 55 or larger tank..Just the price of LR and LS alone is a lot less....if you do it properly. It may be an extreme, but I think a small setup is ideal for a beginer...Yes in the beginnning smaller is harder to setup and keep, mainly with temp swings etc, but its still no diferent than large setups. I believe getting ones feet wet with a PICO or NANO and being able to keep it properly, and if the bug for the hobby still exists further down the road, then go larger.....I started with numerous PICO sized setups, which I still have and doing just fine, and eventually graduated up to larger with a 210 gal being the largest, and my favorites are still, like I stated earlier PICO's.