The tank should be maintained as an environment as near to natural as possible, so a certain amount of care and observation is needed. Fish suffer as much stress as do humans, if their area is dirty; however more fish are killed through poor cleaning procedures than by neglect. They die through no cleaning, theydie through too much cleaning solution.
The fish are swimming constantly on or near the surface. There is a good chance you will mix this up with greedy fish wanting food. So you put more food in which adds to the problem. The fish will not eat the food, but will quickly float back to the surface. The water smells sour and acidic and it is dirty. Put some into a clean white cup and you will see, it has "clumps" of sediment in it. This is the stuff which is turning the ornaments and the side of the tank brown.
This is also the stuff which is taking up all the oxygen in your tank water.
In neither of the above situations will additional aeration of the water be sufficient. The only answer is a tank clean
All your buckets, scratchy cloths, nets, should be clean and only used specifically for your fish. They should not have been near any bleach or detergents. So don’t use a bucket which has been used to bleach clothes. Change carbon and fibre filters at each water change.
Sterilisation of equipment
1.Take a very strong solution of salt water and soak the buckets, etc in it after each use.
2.Take a bucket of water from your tank and net your fish into it, their body temperature will not be affected by a strong temperature difference in the water.
3.To this water add a spoon or so of sea salt -dessertspoon for preference, per bucket. This cleans them of parasites and any fungal spores and infections. The less you handle them physically the less chance they will get fungal infections, as the protective sheath of mucus will not be disturbed.
4.Now take a piece of rubber tubing and siphon the tank water into another bucket and tip it away. You siphon by sucking into the tube until the water touches your lips. The bucket should be below the tank so the water
flows freely. Do this until the tank is empty.
5.Take a bucket of salt water and put the ornaments in to this after rinsing off under a running tap. Also rinse any plants, if they can be disturbed. If you have plants well rooted in the gravel, you will have to flush the tank with clean water and keep siphoning it out until it is clean. Remember that the plants need the slime as food, so it is a case of care and balance. You will not be able to remove the bottom filter if the plants are really well established, but take the air line and push the air underneath to flush out the bottom filter soil as you siphon.
Salt water will not damage your plants in the way you are using it here, as sterilant. The filters should be removed, and all that black slime underneath the filter, removed. Usually a good rinse underneath a running tap is a good enough clean, but they too can be soaked in salt water. Also treat air lines, air stones, and pumps and tank heaters. The gravel should be rinsed off until the water runs clear, and it too left in salt water soak.
6.Now take the scratchy cloth and with a level of salt water in the bottom of the tank, scrub around the walls and base of the tank to remove the last of the soiling. Empty the tank and rinse with clean water.
