Re: Swollen gills on glo light tetra
#4
A couple of things spring to mind. First is that running a new filter alongside an existing one doesn't guarantee thet the new filter will be colonised by bacteria. Basically, there will only ever be just enough to deal with the waste in the tank. They are living in the existing filter, fairly firmly "glued" to the filter media and have no reason to move to the new filter so it's possible that now the old filter has been removed your tank is cycling from scratch again. This would fit as the fish is showing typical symptoms of ammonia poisoning.
Did you test the water at all between the point where you removed the old filter and the point where you started these water changes? If so, what were the results?
Your nitrate level is very low considering the amount of stock you have and the low amount of water changes you do as standard, which points either to a problem with the cycle or to a problem with the nitrate test. Can you retest everything making sure to follow the directions very precisely and giving the nitrate test bottle #2 a full 30 seconds very vigorous banging and shaking before adding the drops and then giving the test tube a full and very vigorous one minute shake.
Golden Barbs (
Puntius semifasciolatus) are really a bit big for your tank. They need about a 3ft tank to swim properly and are temperate fish rather than tropical. At 25C your water is rather warm for them. They do best at around 20-22C and the maximum for them (though short term only) is 24C.
With four Golden Barbs totalling 32cm, four
Corydoras sterbai totalling 26cm and six Glowlights adding up to another 24cm you have 82cms of fish in your tank. After displacement for gravel, decor etc you have approximately 55 litres of water and for a fully mature tank the absolute maximum amount of fish is 1cm per litre so you are quite overstocked. That makes the low nitrate reading very strange especially as you are only changing 10L of water per week.
In a normally stocked tank, 25% is the recommended minimum amount of water to change to keep nitrates in check (15 litres), but when overstocked that usually needs to be more.
As the Golden Barbs aren't really compatible with the other fish in terms of water temperature, need a larger shoal to thrive and really are too big for the tank, it would be a good idea to try and rehome them. It would also be better for your Cories to add another two to bring their number up to six, as they do better in groups of at least six.
Retest carefully and let us know what you find, as there seems to be some issue with the test results so far.