Dwarf Gourami Problem With Male Bullying Female

Dwarf gouramis are notorious for this, unfortunately. If he wants to breed and she doesn't, it has been known for the male to actually attack and kill her. The usual remedy is to have at least two females, and lots of tall plants (real or synthetic) to give the females somewhere to hide.
Your male gourami will be OK on his own if you don't want to risk getting any more females.

But it could have been natural causes - dwarf gouramis are prone to illness. Was she showing any physical symptoms, besides hiding away?

I have a male and a female on advice from
Lfs when went for single male... He chases he around but she is fairly bold... Is there
Anything you would recommend before anything bad happens to her. It doesn't happen all the time but this post made me concerned.....

It sounds as if maybe another female in the tank would be a good idea Naomi, Thanks for the advice Sue. I am planning to change the substrate this weekend for black sand (for my corydoras to play in and prevent the high PH pikes I'm getting with my gravel) with Fluval Stratum underneath - then I'm getting some lovely new plants and after some time I may feel brave enough to get a couple of females.

Thanks again Sue. I did wonder about losing bacteria on the sustrate. There is quite a lot of gravel in there! Maybe I could put some just in a bag in the new tank for a few weeks until the new substrate builds its own bacteria? I do have an extneral Eheim filter with lots of lovely ceramic filter bits in. But I will monitor the ammonia and nitrite levels. Fingers crossed! 
 

They do like to sell them in pairs and have a powder blue male and female... Very good store who can tell them apart... Should I get another 2 females if will only sell in pairs? Concern in 90 litre tank may be too many!!!

It's strange that dwarf gouramis are often recommended as ideal community fish, but there seem to be more people with problems with them than almost any other fish. Without a female, he could just turn his bullying on to other fish.

There is a theory, held by a number of very experienced fishkeepers, that most people keep their tanks at too high a temperature. The idea is that the commonly "recommended" temperatures actually represent breeding temperatures rather than those for normal maintenance. By keeping fish at a high temperature they are in a permanent state of "breeding readiness" which stresses them out over time. So if you have an oversexed male gourami and are keeping it at a temperature near to the top end of normal, dropping it by a couple of degrees might calm him down and make him less aggressive.

There's a very interesting article on the Seriously fish site (Knowledge Base/ Beginner's Guide) titled "Whaddya mean, too hot?" It's food for thought and well worth anybody reading.

In my youthful fish keeping days, many years ago, our thermostats were always set to 20 - 21 deg C, which I believe was considered normal then. I have wondered if this was why our fish seemed to survive and live comfortably and healthily without much filtration, water changes or similar.

I always keep a spare heater just in case, but failing that I suggest you take the heater out of the temporary tank which you then wrap in a blanket or duvet. Water retains its heat for much longer than you expect and should cool down very slowly if the tank is insulated like this. It would also hep if you keep the lights on, assuming you have normal fluorescent tubes. I set up one tank and planted it at room temperature of 18 degrees. I took the new heater out of its box, dropped and broke it. So I was temporarily without a heater (which is why I now keep a spare). Anyway, I turned on the lights, and the filter to circulate the water. After four hours the temperature had risen to 22 degrees, 4 degrees above room temperature, entirely because of the heat from the lights, though I understand most of this heat comes from the ballast rather than the tubes. So keeping the lights on does help.
That's all I can suggest.

I'm sure Sue will be better able to answer that than I am. I'll leave it to her.

Tank is a bit full for 2 more large fish so will leave it for now and just hope she's ok!!