Hi guys! I've kept fish in a small 35l tank for about 15/18m and recently upgraded to a 80l aquaoak that I love! We had poor advice at the store and as a result lost a lot of fish we bought for it (they advised no need for air stone and so lack of oxygen killed a litt of them! 😪). We have been given a credit note to replace them now I've resolved the problem so what would you get? Currently only 2 platties & 4 guppies in thrre... I wasn't too replace the tetras I had BUT... How many is too many? I don't want to over stock the task as these surviving fish are all happy and healthy now there is an air stone in there! Thanks in advance!
It's actually very unlikely that a lack of an air pump caused the deaths. Many fishkeepers don't use air pumps at all as the rippling from the filter return is plenty to give good oxygen exchange. As you say you added a lot of fish to the new tank, that is most likely to be the reason for the deaths. Adding too many fish at once causes ammonia and nitrite to spike and poisons fish. Also, did you move over the filter or filter media from the old tank? If you didn't then you had no beneficial bacteria to process fish waste and again, ammonia and nitrite poisoning would be the result.
Now, when it comes to adding new fish the first thing we need to know is whether your water is hard or soft and what the pH is. This is because not all fish like the same type of water - guppies and platys like hard water, tetras like soft water. You can find your water hardness on your supplier's web site if you don't have a gH/kH test kit. For the pH, test a sample of tap water that's been left to stand for 24 hours.
Thank you for your reply. We did use the old filter media to ensure the bacteria was established. The advice we were given was that the pump needed to be under the water (so no air flow!) On the morning of the sad day I plugged in the air stone as they appeared to be gasping for air at the surface and then I did a water test and the levels were all within the usual parameters... The store who sold us the tank and fish have given us a voucher to replace the fish so I'll restock the tank in phases this time to ensure levels are stable. How many fish would be the max for this size of aquarium?