My 3.5" ranchu is in about 18 gallons of water right now, a long flat tub tank with lots of surface area. His only other tankmates are 3 zebra danios. I have a UGF that is being powered by an anemone ornament (my airpump for the other half of the UGF broke), and I think my fishy is overwhelming the filtration a little bit. I am wondering a couple things:

1. I have a tub that I could put about 20-25 gallons of water in, but it wouldn't increase surface area. If anything it will decrease the surface area to volume ratio. Should I move him to that? Alternatively, should I try to find something that has more suface area and more water volume simultaniously since he needs a low current?

2. I am going to have to invest in a better air pump and make a sponge filter whether I move him or not. Should I ditch the UGF and use a really big sponge filter instead? I am a UGF fan normally, but it doesn't seem like I can keep the current low enough and still have it effective. He also keeps uncovering half of it somehow, which is a pain. The only problem I can think of with switching to a mega-sponge is that it might take up a lot of tank space and defeat the purpose of a bigger tub unless its a LOT bigger.

What advice do the gurus have? I am not sure what to do here and I don't want to wind up stunting my goldie's growth or anything

Well personally i dont like UGF, they are messy and i'm really not sure that 1 of these alone will be enough filtration for your ranchu (you said you felt it wasn't enough) I think the tank you have is ok (goldies like a larger surface area). But i'm not sure what you mean by a "sponge" filter, do you mean an internal power filter that has a sponge in it? or one of those dodgy air driven ones?

I would look into purchasing a HOB (hang on back) filter (unless your tank is too shallow?), you can use this in conjunction with your UGF if you want to keep it, but as i said i dont think the UGF alone will be enough and i find them more work than they're worth.

I dont think moving him into a bigger thank will do much, he already has a whole 18gallons to himself (well basically )! Ranchus aren't well known for growing into beefcakes like comets/commons so i wouldn't worry about that, unless you are thinking about getting a HOB filter and it wont fit on the 18g.

Edit: i dont know where you live but have a look at www.bigalsonline.com if your are in USA (i'm not and am very jealous of big als.....) they have filters are very reasonable prices.

Thanks for the tank size advice! I guess I can stop worrying about the size for a while.

The UGF had been enough with the two air pumps, but when one died it basically put it down to 1/2 a UGF filtration, and I'm getting sick of putting the gravel back where it should be each morning lol normally UGFs work great for me. I was thinking of going the corner-filter, airt-driven sponge rout. I have had good luck with those in other tanks...again, not using a standard setup, which is why I would make my own or get one and tack extra stuff onto it. I have a tank with a bunch of 4" snails that make a much bigger mess than my goldie, and a sponge filter has worked with them so far.

I was edgy about getting a powrhead-driven filter because it would up the current quite a lot, and I've seen what happens to the ranchus at pet stores in high currents zeplins in a tornado. I have another tank that is going to be dismantled soon (temporary snail-holding setup) that has a small HOTB filter that *might* work. The only problem is that I have about 5-6" of wall sticking up above the waterline so the danios don't decide to go exploring. I'm not sure the HOTB would be able to get enough suction sitting that far up from the surface, since normally it has to be within 2" to function.

I personally am not a big fan of the UGF either.They hold entirely too much muck underneath,and in the long run can be quite dangerous for holding Aeromona pockets. I'm all for the HOB's.If you go for the nicer ones,they have controls to turn down the current some,and there have also been alot of tips on how to help decorate your tank,in order to cut down on one thrashing stream of current.My Lionheads have no problems at all with any of the HoB's in the tanks,and all my tank's go over the ten x's filtration. I do have to admit that I have Louie,my one eyed Lionhead in an Eclipse 12,and I wasn't happy with the filtration on it.I added a sponge filter in that tank.Although it's not the most flattering,it works rasther well. Between the two filter's,there's alot of movement,but Louie does fine.