ecologystudent

A short introduction first (I've bolded questions so you can find them more easily):

I've been keeping fishes since I was 8 (started by accidentally breeding betas in a 1 gal hexagon {followed by raising all the babies to adulthood}) and I am a fan of simplicity and low tech (but fancy fish). One of my favorite tanks of my youth was a 15 gallon(long) that housed zebra danios which decided to breed after months of no water changes, very low light and near neglectful feeding. The secret? Lots of java moss, drift wood, and having a functioning ecosystem. I've been mostly out of the hobby during my years of college (ram cichlids don't like 6 hr drives every few months), but now I am planning a glorious reentry.

What I want to do is set up an ultra-low tech tank. The only electric device I want on my tank is a light (Unless I can get a window, that is). No heater, no filter. Lots of hardy, undemanding plants that still look good. I like crypts and sagittaria, and they've done well for me in the past. Any other suggestions?

For substrate, I'm currently considering either my mom's method (basically a lot of plants, an inch of gravel, and encouraging a thick layer of mulm) or the soil-under-sand method. Since my mom's farm is organic, and there are areas that haven't been cultivated in 15 years (includes a creek), do you think that it'd be alright to use soil from there? Would it be a bad idea to get soil from around/in the creek, and then cook it in the oven to make sure I'm not introducing anything that would hurt my fish?


Now my main question is this: what fish would you put in a room temperature tank? Temp. would probably range between 69 and 75, but may occasionally dip as low as 65 (though I doubt it). I've had good experiences with zebra danios, but I'd like something a little bigger, perhaps, and more colorful. Apparently killis adapt well to the cooler tanks. Any other suggestions?

I don't know yet how big the tank will be (somewhere between 10 and 50 gallons...) so a wide range of size would be good.

Thanks!