I have 8 Gallon fresh Water Tank with 7 Tiger Barb and 1 Blue Garumi . It is working from last 3 months. Water parameter are Ammonia zero, Nitrite zero and nitrate 40.

Fish are enjoying and going all good But I have some question. I have seen some green powder type in one corner of tank it is very less and same thing i found in filter when i took it out for cleaning. What it can be and how can I rid of it??

Another thing I want to know all fish are going good but 1 of my tiger barb is more fat and swimming vertically and he/she is also vibrating while swimming. But at only some time it is swimming okay Why is it so ??

Third question I have heard about some fish that eat dirt of the water and helps in filtration. What is that fish name and did it will be compatible with my tiger barb and is it worthful to add in my tank.

Sorry I ask lot question But I have some curiosities about all those thing so.

But Thanks to this forum as I learn from here only how to maintain good Aquarium

Will first off you may have some green algea and that is common, just wipe it off. Second you said you have a 8gal tank, that is going to be way to small for the Blue Gourami they grow anywhere between 4.5" to 6" and a min of 20 gal tank is required. the barbs you have will work nice in there. As, far cleaner fish, some small corys would work best. Try and find a micro cory, in a small tank like yours they would be perfect. they like to be in groups of 6 or more but the micro only get 1/2 to 3/4 " with a very small bioload. they are hard to find locallly but can be order online. For you sick fish you should remove them from the rest and put in QT that way you can treat him for parasites. It sound like it has an air blatter problems, but not being able to see it, I'm just guessing. You should be changing 30% of the water weekly, you seid your nitrates are 40 and that is deadly to your fish anything 20 and above. Do a Water Change ASAP

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Gold Coast Aquarium Society South Florida
www.goldcoastaquarium.org

Great Answer. Keep it up Brawo. Thanx a lot you gave me best answer. I am very happy.