Invertebrate for fresh water community? (not shrimp/snail)

[plextor]

Hey folks, I've been looking at getting a new invertebrate for my community tank. It is a 10 gallon tank and houses a bunch of ghost shrimp, four African Dwarf frogs, 1 Apple Snail, 2 fancy tail goldfish, 1 Black Moor, and a small catfish (don't remember name). They all seem to get along (although the fancy tail and black moor are always pecking around for food, scaring off shrimp and annoying the frogs). Since I already have a good amount of shrimp, I'd like to include another interesting invertebrate.

I've looked up Dwarf crayfish, who seems to hold a good reputation as a peaceful creature. But the predatory nature of crayfish makes me worried that it could/would damage the lazy dwarf frogs. Can anybody confirm or denounce my worries?

I've also considered crabs, but most seem to require brackish water and access to air. I'd be able to fix up an access to land, but the brackish water is incompatible with the frogs.
Thanks in advance!

[Sarkazmo]

You're way over stocked now. You need a much larger tank for goldfish than you do for tropicals. Goldfish pump out an enormous amount of waste and get huge. I can't in good conscience recommend anything but a larger tank.

Sark

[Michael Milligan]

Put the goldfish in a bigger tank if you want everything to do well. If they are still small, then a 20gal will be ok for a couple years.

The other option is to give the goldfish away or trade them on Craigslist. You can get tanks there for almost nothing if you have a car to pick them up!

[plextor]

Thanks for the responses!
Yesterday I had my water tested, and indeed the nitrate levels were indeed too high. The guy at the store recommended me a bottle of good bacteria that will speed up the nitrogen cycle. Does anyone know if plants are significant in the cycle? I’ve read that plants are to flourish from nitrates converted from the good bacteria.
I won’t be able to remove the Black Moor or fancy tails because they are the favorites of my sons, but I’ve been looking at getting a bigger (maybe a 15 gallon if it’ll fit in the 10 gallon’s previous spot).
For future reference, can anybody with personal experience tell me if a dwarf cray will attack my dwarf frogs? I have plenty of shrubbery that will allow frogs to hide in higher positions from the bottom-dwelling cray, but I don’t want to add stress to them or factor in any possibility of casualties.

[Brhino]

I won’t be able to remove the Black Moor or fancy tails because they are the favorites of my sons, but I’ve been looking at getting a bigger (maybe a 15 gallon if it’ll fit in the 10 gallon’s previous spot).

I want to emphasize this because it's an issue we get this all the time. I'm sorry if this sounds cruel, but it's the honest truth:

10 gallons is WAY too small for two goldfish. 15 gallons is still way too small. If you don't find a better home for them (either in your house or somewhere else), you will have to deal with the fact that your sons' favorite fish have succumbed to illness and died.

[Brhino]

oops, I misread, you have 3 goldfish, not two. That makes the situation all the more dire. The general recommendation for 3 fancy goldfish would be 40g minimum, to say nothing of all the rest of the creatures you have in your tank. The "small catfish" could be a concern too, depending on the species. Some small catfish turn into very big catfish.

[plextor]

Wow, I didn't know that the goldfish produced so much waste(should have known from their ravenous appetite). I will try to give the two fancy tails to a friend; would the black moor be okay in a 10 gallon?

[Brhino]

20 gallons is the recommended minimum for a single fancy goldfish. I'm sure the black moor is small now, but they can reach up to 10" in length and will suffer from a host of health issues if not given sufficient space to do so.

[HEADIN]

Have considered a blue cray myself but after asking about them on here and doing plenty of reading, ive decided against. To many of my fish would be at risk from it and they will eat what they can catch. Especially in the dark wen sleeping.

Ive read that dwarf crays grow to a max of 2ins and are much more peaceful and less likely to try to catch the average sized fish because of their small size.

Cant find much info on them though to do proper research or anywhere that sells them.

[Gisela]

You also have a problem with the right temp's for the different species. Goldfish like it cool, catfish and frogs warmer.