Gourami doing odd things

Question
Hi Ron,

I have a 20 gallon community tank, setup for about 9 months now.  Contains 8 neon, 8 harlequin rasbora, 7 small platy (and one baby), 3 small catfish that prowl the bottom, 3 green tiger barb, and 2 rainbow gourami.  Quite a lot of low-level live planting, and a few ornaments.

Usually I'll change about two or three buckets (6 to 9 gallons - 30% to 40%) of the water every couple of weeks, when I vacuum the gravel.  The plants seem to keep the nitrate level at about 100mg/l.  Temperature kept at about 22 degrees although it's got warmer lately with the weather being hot, it was 24 today before I changed the water and put some cool in.

One of the gourami has started having the occasional 'mad dash' into the gravel, where it'll dig about, all round the tank, and it'll even jump out of the water (where it hits itself on the glass cover).  This will last about ten seconds, and then it'll go very quiet.  It just spirals down to the bottom, or up to the top, and remains motionless.  I though it was dead once.

It then seems perfectly ok again, sometimes for hours, although it does hide a bit more than usual.

All the fish are ok - beautiful deep colours, delicately shaded fins with no damage, and they all get along well with no chasing and nipping.

I've lost very few fish in this tank, three of the four platy that I started off with died in the months since it was setup (the last one only recently) but I put this down to a poor purchase.  They have been the only casualties, and never looked totally happy unlike everything else in there.

Recently I've gradually increased the pH from about 6.7 to 7, and the hardness from 6 to about 10, over a period of about a week because it seemed on the edge of tolerance for platy, and the 6 new ones I got 3 weeks ago still seem happy.

The tiger barb dance with each other in circles occasioanlly (2 female and 1 male) and the new platy are also exhibiting breeding behaviour, chasing each other about and playing hiding games in the plants (one of them looks pregnant) so there's probably nothing wrong with the water chemistry, nothing shows up odd on the test strips I use.

I'm in the process of changing the filter over from undergravel to an external one (the small eheim) so I have both at the moment.  The nitrites have gone up from zero, which is where they normally sit, to 1mg/l, and I keep turning the undergravel uplift pump back on to keep it low when necessary until the new filter media develops.  I seeded the external filter with gravel from the tank, so it should pick up quickly.  I don't think it's this because the gourami started behaving a bit odd before I did that, when the nitrites were zero.

There's a carbon pad in the new filter at the moment, which the old gravel filter system never had of course.  Can't see how that would be bad.

They generally get fed flake, although I keep a supply of various frozen food, so they'll get a cube of something tasty now and again as a treat.

When I lived elsewhere I kept aquarium fish for several years without a problem, and had a pond with coldwater fish too with great success, so I'm not used to recognising many fish problems, fortunately I've never really had any.

Maybe it's just their breeding behaviour, I've never seen it, but then these are the first gourami I've kept.

:-)

Steve

Answer
Hi Steve,
 That is an interesting one.  From the sounds of it, the problem is internal to the gouramis, given that the rest of the fish seem fine.   That definitely isn't mating behaviour, unfortunately.

 The one thing that strikes me as odd is the idea of gradually converting from an undergravel to another type of filtration.  Basically, you need to take out the undergravel plates because if you do not, that is going to create a real toxic wasteland on the bottom of the tank.  I am also unclear about what you mean when you say that you turn the undergravel filter back on -- if you have an undergravel filter, you need to keep it running all the time.  

 I have never found a good way to remove an undergravel filter short of disassembling the tank -- it is very messy and that is one of the reasons I never use them anymore.

-- Ron
  rcoleman@cichlidresearch.com
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