Suggestions for a freshwater destritivore?

[microcosm]

I wonder if anyone has any suggestions for a detritivore for a freshwater project I'm re-starting.
I've been trying to build a self-sustaining microcosm. I've been looking for critters that can tolerate low oxygen and temperature fluctuations to populate this thing, and I think I have most of it figured out. I've got some plants to oxygenate the water somewhat and provide a food source; a snail to take care of algae; pondwater and sediment to liven up the gravel and do some recycling; and of course, a few fish to enjoy it all.
Here are the species I've settled on so far: a bunch of Elodea, since these aren't particularly demanding about light requirements; one trapdoor snail, since they're live-bearers and won't overrun the small tank with little ones, and seem to be relatively hardy; five white-cloud mountain minnows, which seem to do well in just about any conditions; and God knows what microorganisms I scooped out of this pond.
The last thing on my list is a detritivore. I've tried ghost shrimp, because I understood they were supposed to be pretty hardy. I started out with three, but eventually they ate each other until there was only one. I don't know if they were killing each other, or just eating one another when they find one of their buddies dead during their normal detritivore activities. Anyway, I thought maybe they were killing each other and maybe I had too many of them stocked? It's about a three-gallon tank. So I left that last one in there, but eventually after a couple months it died too. If I put another lone shrimp in there, it eventually dies, so obviously this isn't a good long-term habitat for these guys.
So, if anyone has any suggestions what I could do with the tank for the ghost shrimp to live and be happy, or if anyone has a suggestion for a different type of detritivore, I'd appreciate it.
The tank is just as I described. About three gallons. Gravel with live microorganisms from a pond, pond water (topped off with distilled water everyone once in a while to make up for evaporation), plants, a snail, and five small fish. The water is unfiltered, unheated, and I don't change the water. For the most part the critters eat the plant material growing in the tank, though periodically (once every week or two) I toss in some fish flakes just to liven things up.


Thanks.

 

[triazole]

lack of calcium could be a reason the ghosts don't do well. i have never had good luck with keeping ghosts too.
perhaps a bamboo shrimp (though i believe it'll become too big for a 3g tank). nothing else comes to mind at this point.

 

[coldmachineUK]

Hi, I'm not sure I can help with the answer to your question, and I don't want to be a 'party pooper' but a couple of things raised alarm bells with me:

1. "God knows what microorganisms I scooped out of this pond". I would be concerned primarily about external parasites. I have seen this before when a meddlesome parent opted to put some plants from an outdoor pond into an indoor tank a friend was keeping (3' coldwater, never really liked coldwater myself but still). The infestation was so terrible she had to pick each fish out of the tank and use tweezers to remove them. A lot are still scarred from the experience. I would not recommend you using outdoor pond water in an indoor tank with fish you are buying from an LFS like white cloud mountain minnows...

2. About the mountain minnows. They are hardy, yes. Hardy in the same way mollies and platies are. That doesn't mean they are 'invincible' though. They are a river fish, needing lots of fast flowing cool water (temp can be upped to say 25c at a push if you were keeping a tropical set up). Fish can be kept in less than ideal conditions when it comes to things like temperature, pH and so on. But keeping them in outdoor pond water...well...I'm just not so sure about that. You also mention low oxygen requirements. River fish need very high oxygen levels because the fast flowing water is more saturated with o2 as a result. Again, this raises issues with the minnows. One last point: 3G for 5 minnows + the other inhabitants? Well, it sounds like a tight squeeze to me...

My question is: if you have a pond, why not use it as one. If you have a tank, why not use it as one. I don't understand the idea of mixing them.
Best of luck though, and hope it works out.

 

[microcosm]

Thanks for the bamboo shrimp suggestion. 8-12 cm does sound a bit large for a 3 g tank. I'll look into the calcium suggestion a bit more.

And thanks for the warning about parasites from pond water. As far as I know this might well be the problem for the shrimp. But as for the minnows, they've been living in this setup for about a year and a half now, so if I had to guess, I'd say probably they're doing alright in there.

 

[hc8719]

; one trapdoor snail, since they're live-bearers and won't overrun the small tank with little ones

you do know that live bearing means, they breed faster?

 

[Mosaic]

Snails can do the work of a detritivore. They eat more than just algae.

I'm doing the same thing with a 2.5 g. It's a very interesting project, and it's at the point where it's essentially self-sustaining. I haven't fed it for weeks, but the snails (and some other little critters) are still reproducing.
My ghost shrimp died after 3 weeks, and I'm not really sure why either. However, I am going the fishless route with it because I thought it was irrepsonsible to keep one in something so small and so... experimental. The water parameters do really crazy things at times, so keep an eye on that.
The plants are doing great though. I have several species and they're doing better in this tank than in any of my higher tech tanks. I don't worry about light since it gets sunlight most of the day. Interestingly, algae has not been a problem at all. I mean, not a single spot of it.

At set up, about 6 weeks ago:

Today:

Note this is after I took out *3* species and added them to other tanks because they over ran this one. What's left in here are the plants that I cannot keep alive in my other tanks for some reason. I still have to trim it regularly. Check out how much bigger the crypt is on the right! The wisteria's progress (right behind the crypt) is pretty nice too.

I want to see pics of yours! We can compare notes

 

[microcosm]

Live-bearing means they reproduce faster? I thought live-bearing means they bear live young, instead of laying eggs. Anyway, my trapdoor snail reproduced a couple times, so I used to have one large and two smail snails eating their way around the tank until the mama died. I haven't seen the outrageous explosion of hundreds of tiny snails I've seen in some other tanks.

Mosaic, I would be interested in comparing notes. Unfortunately I can't post pictures of my setup because I moved across the country recently and left the microcosm behind because I was afraid it wouldn't survive the trip. I gave the whole thing to my mother. The first one is still doing well, and now I'm starting over.
I was reasonably happy with most of my original choices. I had to put a few fish in there to have something a little lively. (I saw a large, completely sealed glass microcosm that had fish in it. Must have been a few hundred gallons, at an aquarium somewhere and thought that was about the coolest thing I'd seen.) It seems the white cloud mountain minnows were a reasonable choice: small, tolerant of oxygen levels and temperature shifts, able to live off the plant material in the tank, not particularly aggressive. coldmachineUK's comment about their natural habitat makes sense, though, even if they have survived in the old setup this long; maybe there's something else that would find it even more agreeable. Did you look into fish at all, or had you precluded the idea before you got started?
Also, how did you stock your tank with microorganisms? I read one web site about microcosms that suggested going out and finding the healthiest looking pond you could find, and start your tank on water taken from there. I also took up a little sediment to liven up the gravel. Again, coldmachineUK's comment about possibly introducing parasites could be a consideration, though I didn't see any evidence that this was an issue in my old setup. I've seen microorganisms for sale for saltwater setups, but I've never seen them for freshwater, so I don't know what other option there is.
The Elodea in my old setup did great. I kept the thing out of direct sun so as to avoid temperature fluctuations, but the plants went wild in indirect sun anyway. I had to trim and remove material several times.
What species are you keeping in yours?

 

[Mosaic]

Well, just think of how much faster livebearer fish reproduce. But you won't get a snail explosion unless you add food to it. My snail population is pretty stable at around a dozen since they just live off the dead plant matter, and there's not much of it in there.

Size was my main consideration for deciding against the fish, since its only 2.5 g, and a lot of that space is taken up by the plants. Now I'm glad I didn't put them in because they'd surely be dead. My ammonia levels have never completely gone down. I think the garden soil I use for the substrate has something to do with it. It either leaches ammonia or something else that the tests read as ammonia. People here suggested that since I have no filter and no fish to circulate the water that toxins are building up or I've got anaerobic pockets or something. So maybe fish would be a good thing, but I definitely don't think I'd keep them without doing water changes, but then the tank wouldn't be self-sustaining. It all depends on how much of a purist you want to be about it, but fish do add another level of responsiblity.
I don't know if you'd have similar problems using sediment from the wild; it's possible you could leach chemicals you couldn't even test for. Plus, what if there were leeches or something in the sediment? I know I wouldn't want to stick my hands in the tank to do any kind of maintenance.
As for the microorganisms, are you talking about the nitrifying bacteria? I added a layer of fine gravel from my older tank on top of the soil. But I also had some other tiny critters pop up in the tank. I have some sort of ostracods or copepods zooming around (I always get em mixed up), some very very tiny white wiggly things, and one slightly larger bristly worm that's no longer there (thank goodness. it was gross). I think all these came in with the plants and only survived because there were no fish to eat them. I think a waterbug would be pretty cool though.
Right now I have Rotala, Cryptocoryne wendtii, Myriophyllum sp., wisteria, and what's probably a melon sword. They've all done really well; I was actually really surprised to compare the two photos. I had to take out the cabomba, water sprite, and ludwigia when it outgrew the tank and because I want to do some aquascaping eventually.

I want to see how you set up your new one, so take pics when you get ip up! How long has your old one been set up? Got any tips?