gourami fish

Question
Hi,
I've a small fish bowl, which is 12 inches big. I've some pebbles in the base and had put 6 gourami fishes. a pair of blue gourami, a pair of red gourami (which is more brownish) and a pair of kissing gourami. There is no filter, however, i change the water once in 8 to 10 days. First one week i feed them pellets and later dried blood worms, past three days.
Two days back one of the red gourami was dead. i dont know what actually happend and today the second red gourami died. Though they are known to be peaceful, the blue ones have been very aggressive and running behind each other. Both of them are males.

The weather has changed here in past two days. it has started to rain a lot. i understand that they don't survive in cold water.
I would like to know how to keep the temperature warm, i do not have an ac in my room. the fan normally remains on. i dont want the other 4 to die. i would like to know what could be the reason the other two died for, i know it would be impossible for u to know that, but any tips on how to keep the others alive.
I also got the sand, usally the stone gravels that are small, should i replace them with the pebbels. Also should i plant some artificial plants to create some hide out space for them.
Any tips from you for their keeping would be very much appreciated and i would be really thankful to you.
Hope to hear from you.
Thank you very much.
Jiten.

Answer
Hi Jiten;

Your tank is just too small for them to be all together. Especially without a filter. The minimum tank size for dwarf gouramis is about the size you have, but that's just for one pair. You would need at least a 20 gallon for six gouramis with lots of hiding places, even if they are the dwarf variety. Male gouramis of all types are aggressive towards each other so they just can't live in such small spaces together. The more dominant fish of the group has probably killed the weakest and he will continue to do so. Sometimes they even harrass their females to death too. The only real solution to your problem is to get a larger tank and you can put a heater in it too. They are thermostatically controlled so it keeps the temperature constant. Change 25% of the water twice a week until you have a filter. Normally, tanks need a 25% change once a week but your tank needs more right now because you have so many fish in such a small space without a filter.

Whatever gravel you want to use is up to you as long as you can keep it clean. Don't let waste build up in it. The way to do that in all tanks is to vacuum it once a week with your weekly water change.

Put lots of plants in the tank to help them hide from each other. Do the same in your larger tank once you get it set up. They may or may not be able to live together even with a larger tank and lots of hiding places.

Dwarf gouramis are usually okay with other fish but males just don't tolerate each other.

Good luck...

At Your Service;
Chris Robbins