Zagz
Aquarium Advice Addict
It sounds to me like the tank is suffering from an ammonia or nitrite spike, causing the fish's gills to suffer damage and hence the need for oxygen. I must agree that the test kit is a necessity. Without knowing your water parameters it will be next to impossible to figure out the cause, as the likelihood the cause is the water parameters.
I recently changed the substrate in my established for 6 months 15 gal tank and suffered a mini cycle as a result. Fortunately I was testing the water and no fish died. Had I not tested my water my fish most certainly would have died from ammonia and nitrite increases. With no water test kit I would recommend if you are planning on adding more fish to do water changes every day until you get a test kit. I also agree with jrp that the chemical to remove the cloudiness may have affected your water parameters. I have goldies and they are messy and if I don't do water changes every few days the water gets cloudy fast. I use active carbon in their filter as it helps some.
I recently changed the substrate in my established for 6 months 15 gal tank and suffered a mini cycle as a result. Fortunately I was testing the water and no fish died. Had I not tested my water my fish most certainly would have died from ammonia and nitrite increases. With no water test kit I would recommend if you are planning on adding more fish to do water changes every day until you get a test kit. I also agree with jrp that the chemical to remove the cloudiness may have affected your water parameters. I have goldies and they are messy and if I don't do water changes every few days the water gets cloudy fast. I use active carbon in their filter as it helps some.