tropical tank

Question
Hello Chris, This will seem like an odd question I know, but I am worried about my aquarium.  I have a small tank at the moment it only holds about 22 litres of water, I think it is plastic, it is temporary till I get a four to six foot tank.  This tank was used for an Axolotl when our axie died we cleaned out the tank and it is now used as a tank for tropical fish.  It has only been a tropical tank for one week. We have 7 fish in there one very little black ghost knife, one dwarf gourami, two black fin tetra's a small silver(bala?) shark, one little (very fat) cat fish and one platy. The filter is a small 5w 200 l/h filter with charcoal and sponge. Ph is neutral. 20% water changes will be weekly.  The problem is that when the axie was in there the tank had an odd smell to it, I just thought it was the way that axie's smell.  Now that I have my little tropical fish in there the tank smells again.  I have changed the charcoal and the sponge, the tank was washed before we put the fish in, the gravel is new.  Can this smell make my fish sick.  It is a pungent odour, though it is not as strong as when the axie was in there.  Do you have any ideas with this, my local aquarium owner is stumped with this.  Thank you for your time, Veronica

Answer
Hi Morathi;

I am the bearer of bad news I'm afraid. I'm very surprised that your fish store owner is not aware of what I'm about to tell you but your fish are in very serious danger. Unfortunately your little tank is far too small for the types of fish you have, even temporarily. Ammonia is building up in there and that's what you smell. Ammonia is from fish waste. Have your fish store test the tank water for the level of ammonia and you will see what I mean. Normally in an established tank the ammonia is consumed by beneficial bacteria. A new or recently cleaned out tank has no beneficial bacteria growing in it yet. This initial stage of a new tank is called "The Break-in Period", "The Cycle", or "New Tank Syndrome". The break-in period takes 4 to 8 weeks but your tank is too overloaded with fish that are going to grow very large and it just isn't ever going to balance. Unless you are going to have a four to six foot tank ready for them in a couple of days the fish really should go back to the store. For now, change 25% to 50% of the water every single day to hopefully keep them alive until you can get their new tank ready. Here is a link to my page on new tanks that should help you know more about what is happening in there. It will help you get your new bigger tank established too;

http://www.xanga.com/Expert_Fish_Help

Good Luck...

At Your Service;
Chris Robbins