2.5 unfiltered work tank - which invertebrates?

[Sixwing]

So, I've got MTS. *chuckle* What can I say.. my LFS had a sale. :3
I recently purchased a 2.5 gallon tank (my second for work - the other one's in reception, not at my desk), put in some substrate from two established tanks (white sand and Eco-complete, resulting in that salt & pepper look) and planted a bunch of stuff in it.

Stats:
2.5 gallons (12x6x8) All Glass Aquarium
No filter, aeration, or internal gear
Shares a Home Depot desk lamp (you know, the one that's popular on so many little tanks) with a small potted croton - light intensity is easy to change, duration 9 hours (one work shift)
Plants:
7x C. wendtii green (seriously.. one pot, seven healthy crowns and a couple babies I didn't count. They're all little for now, but I fully expect to move them as they mature.)
2x Lobelia cardinalis, also little (3" or so, which I also expect to move as they mature, or maybe coax into growing emersed? Google seems to think these cute little fellas will mature into monsters.)
One pot H. callichtroides

I have access to a bunch of other plant species, so if a fast-growing stem or something is needed to suck up nitrates, I can get it.

Water changes will be weekly or more as needed; the water will go to the many potted plants on the desk, so that won't be an issue. The local water conditions out of the tap are:
pH 7.8
GH and KH off the scale - VERY hard, perfect for invertebrates
NH3 0
NO3- 0
NO2- <5

The substrate from my other tanks brought the standard complement of snails: Physa, Planorbidae,and Melanoides,which I think are rather cute and won't be getting rid of. Right now there seem to be two or three of each. I fully expect them to breed like bunnies.

What I'm wanting to know is this:
What kinds of critter can I add without adding a power filter? The power outlet at my desk is full, and I would get in trouble for bringing in my own splitter.

I'm thinking a handful of some color of Neocaridina, or a single/pair Amano shrimp, or maybe even an apple snail. Thoughts?

[bradac56]

I was going to say lots of snails but you already have them.

On further thought you could make a diy non-powered bio-filter out of a spice container or a water bottle and put a few guppies in there.

- Brad

[Sixwing]

Hmm. How would one go about a non-powered biofilter? I thought you had to have water movement for that to work?
Thanks,

[Strick]

Sounds like a perfect home for a betta... Here's the tank I keep at my desk:


2.5 gallons is really too small for almost any other kind of fish. But you could probably keep a dozen or so shrimp in there... very small bioload.

[Sixwing]

Cute little tank, that. :3

I'd rather not do a betta since there's no heater, and this office is consistently cold. I tried keeping one unheated in here for a while, and it didn't work out. He looked so sorry that I ended up moving him to a different (heated) tank.

A dozen shrimp sounds great, though! That's what I wanted to know.
Thanks,