Fishie, my HM, loved his 5 gallon with filter until the filter cartridge got gunky and the water flowed out of the overflow area. This made the water current to strong and he started biting his tail. He's in a temporary 1 gal. hospital tank right now so I can monitor the amount of stress coat I'm giving him while his tail grows back. Also until I can start using my new filter cartridge. He doesn't like it in that 1 gal, though. He's gotten a lot bigger since he used to be in there so if I decided to keep him in a tank without a filter it would have to be a 2.5 gallon long at least. He really loved his 5 gallon, though, until the water current gave him problems.
Lila LOVED the 5 gal. She was originally in the 1 gallon (she was small so she could move around a lot still) and I switched her and Fishie when Fishie started biting his tail. Females are really active so she really liked being able to zip around in the 5 gallon.
Last edited by OrangeAugust; 10-03-2012 at 08:53 AM.
All I know is my PK loves his long low bookshelf tank 6 gallons. He swims fast and furious most of the time. My DT with extremely heavy fins is in a 5 gallon and would probably do well in an even smaller tank. He lays around most of the time.
I wouldn't necessarily say that space is as big a deal for HM's as filter current. I've got Neptune in my 20 gallon tank all by himself right now and he loves it, but it's just got a sponge filter so he doesn't have to work hard to stay in one place. And he does have crazy long, heavy fins. I do think PK's enjoy having a bit more space though, mine is really fast compared to the HM's.
Definitely look into getting a sponge filter fed by an air pump, they're safer for HM's because they don't produce a strong current and they can't suck their fins into the intake and hurt/kill them. I'm not sure if you saw what happened to Lizzie's poor Jonah a few days ago, but these injuries can be brutal and life threatening.
My HM does alright with my Whisper 10i filter. He has places to hide from the current and plants to rest on if he gets tired. I also baffled the filter to death to decrease the current in the tank as much as possible. But even with all the pit stops, my HM uses everey inch of the space my tank gives him.
I like to think that the HM's heavier fins means a 5 gallon or more tank would need the equivalent of park benches scattered around. Even if HMs can be more comfortable in 3 gallons doesn't mean it's impossible to make a 5 gallon tank comfortable. It just takes a little extra work.
More important than volume is the shape of the volume. Deep tanks can be harder for HMs because of their heavy fins, so longer, more horizontal, tank can be easier for their fins in a low-current tank.
SOME HMs don't like a lot of space. mine seem to love it. 8V my three HMs(TECHNICALLY a delta, Rosetail, and DTHM), have bigger tanks(2 gallon, 2 galon, and 1.5 for Twitch, because he's a tail biter). my PK is in a 2 gallon, and my HMPK is in a gallon. so, in my opinion and personal experience, it varies from fish to fish. Lulu, my PK, hates bigger tanks, as does Stephano, the HMPK(he's SUPER shy and feels better in smaller tanks with lots of plants.)...
on the flip side, my first HMPK, Weiss, loved space. zoom all over his 3 gallon!