i have been rearing drawf gourami (colisa laila) for more than 6 months now. todate almost 50 of them had perished since then. it's always the same old case. They will be fine for the first 5 days, then one by one will die. but the females die faster than the males. my tank is around 8 liters big, and at one time there will be 8 of them around. i put real plants, but after sometime, i stick with the fake ones. i found out that the real plants will actually cause them to die. anyway, my filter is the bubble filter inside the tank. i found out that there is the white spot disease affecting them. every 2weeks, i will clean the tank and put RO water. the gravel and other plastic items will be soak in boiling water. this helps a bit, but once a while the fishes will die again. then, i tried putting the blue medicine, but to no avail.sigh...

just wondering, what else can i do??

my suggestions is to keep experimenting with all sorts of fish when I first started looking after goldfish I had them dying on me within days untill I had to change the water and they still died I say do what I did increase your luck by constantly buying fish and eventually they wont die it takes years of practice and expereince to reach looking after these types of fish I would say go for goldfish and cold water fish and increase your experience where I started off I was crap at looking after goldfish then when I first turned 20 i bought myself a tropical tank and I am going to get a 200 gallon tropical tank!!! jeez I am going to be busy and I will start my own breeding shead but they will all die I tell you why because I need to increase my experience even the most experted aquariests have troubles with fish like that dying fish is normal and we just need to except it I say dont just experiment with fish do it with water also and build up to it and never jump into the deep side I dont know you and I dont know how much practice and expereince you have in fish keeping so correct me if I am wrong I may not know but yeah just try that suggestion.

Your fish are dying because of your water conditions.
Firstly, you clean your filter every 2 weeks. You are killing/ removing the beneficial bacteria in the filter. The bacteria in the filter is what breaks down the nitrites and ammonia in the water (from fish waste) and breaking them down into nitrates which real plants in the tank would then use as food to grow. The fish die because the ammonia and nitrites build up in the water and poison the fish.
STOP WASHING YOUR FILTER. The filter material should be gunky and dirty looking - that is what the bacteria thrive on in order to create good water conditions for the fish to live. Only clean it once every 6 months if at all.
The same with the gravel - the gravel will over time accumulate gunk with again contains bacteria which the plants need to thrive in order to create good living conditions for the fish. STOP WASHING THE GRAVEL.
Second, remove the plastic plants and have real plants.
Thirdly, RO water is water with nothing in it - no minerals or trace elements that plants and fish need in order to live let alone thrive. STOP USING RO WATER. Use aged/ dechlorinated tap water instead.
Fourthly, using any sort of medication in your tank kills the bacteria in the filter - no matter what the manufacturer claims.
Finally, your tank is too small for so many fish. At most you should have two gouramis in a tank of that size.
I hope this helps.

well, the main reason i keep cleaning the tank is there are lots of slime on almost every corner of the tank. from what i read, there could be many white spots fungus growing on the slime. how to remove the slime without cleaning the water?

What does the slime look like? Can you give an idea of the colour? Is it just on the sides of the tank? Is it on the plastic plants and on the gravel too? Or perhaps you could post a picture of it?
It all helps towards identifying the problem and coming up with a solution.
Thanks.

the slime are clear color. they are like when you go to the jetty, you can see lots of dangling strings under the water, sticking to the jetty. and it moves following the water current. same like tall grass moving when the wind is blowing. it sticks to almost everywhere, on the glass wall, on the plastics, the live plants leaves and even the chimney of the filter.

Clear slime - no colour? That sounds strange. Perhaps you could post a picture of it.

dwarf gouramis are hardy fishes. I have 4 of em in an empty 8 gallon plastic container without filteration or aeriation watsoever. Just 50% water changes twice a week. and they will still survive (like their famous cousin, the siamese betta fighting fish). Just dont over populate them as they are very territorial fishes (and shy too).

My 2cent worth....

Wash the tank,filter, (and watever gravel/materials) thoroughly clean (disinfect it if u must). dry it out under the sun if possible. get a temporary container, fill in 1/2 with old tank water and 1/2 with new dechlorinated tap water. put your gouramis in their temp home for several days. Aeriate if u want (no need filter). Change 1/2 of the water with new dechlorinated tap water again after a day or two. if you wish, change 1/2 of the water again for the 3rd time after another couple of days. This is to let the gouramis to settle down in the new water chemistry. check the temp home for any signs of slimes... If all is ok, time to move back to old tank.

transfer 1/2 temp home water into the old tank and fill in the other 1/2 with dechlorinated tap water. and setup up the tank as you want. NOTE: you need to RECYCLE the tank all over again. Whether you want to use your gouramis or another sacrifiable fishes to do that dirty job, it is up to you. Change 1/2 the water twice a week to help the gouramis survive the cycle period. They should last longer than a week maybe a year 1/2 or two..

Dwarf Gouramis don't really need a good filtration going on. They come from slow moving waters and the little gunk doesn't really bother them. They aren't very good community fishes and would be good in a tank with their same species. What they do need to thrive though is soft slightly acidic water. A pH of about 6.5. The white fungus you see in the water is mould on organic matter. In a healthy set up this shouldn't occur. You could be overfeeding and you might not have enough water circulation in the tank. To add to that you're cleaning your filter media a bit often. This would be fine if you use old aquarium water instead of tap water. A combination of this practice, overfeeding + washing out the filter with tap water = ammonia. Ammonia is toxic to fishes and is what's proabably stressing and killing your fish.

Try to feed live/frozen foods. Frozen blood worms do just fine. These pollute less and fish tend to finish this up more cleanly. Live, fine floating plants like riccia fluitans/lemna minor will give them a bit of a shelter and will encourage them to build bubble nests and breed as well as help soak up nitrates and keeping the water healthy.

The slime is fine! Every tank in the world has slime! anyone reading this post go to your tank now and slide your finger on the wall....i guarantee youll find slime....go to a river or any antural place where fish live i guarnatee youll find slime.....the slime is harmless...it sounds like you doing too much is the harm..

Secondly.....8 dwarf gouramis CANNOT be in in an 8 liter tank. i suggest you buy a bigger one at least in a 20 liter or your fish will keep dyeing man. Theyre smallbut theyre not tiny either, they need room