Human impact on the oxygen cycle?

Is it tp possible to cycle a tank with low oxygen and no filter?

• I think i just cycled a 5 gallon tank within 2 months. While cycling, i put some yabbies bought at the bait shop to produce ammonia. I only had a air pump and turned it on during the day and turned it off by night. There was no filter. I fed the 2 yabbies every other day. After 2 months, the water was disgusting, all green (algae) and i thought algae would only grow when there is lot of nitrate or nutrients in water. I immediately checked the water and the parameters were perfect. No ammonia, no nitrite but tonnes of nitrate which is easy to fix. I put it a box filter and water cleared up in 1 night. I did a water change then added added baby goldfish, taking the yabbies out. (they're in the pond now) The fish are now doing fine. No sign of stress. Dorsal up, eating and swimming like crazy. I figured that the yabbies most of the oxygen so i thought the tank would never cycle but i think?? it did. Is it possible to cycle a tank with no filter and low oxygen?

• Answer:

  Yes.. what you have down will work, but has some serious limitations. The air pump provides circulation of the water around the tank, the yabbies (freshwater crayfish for the non-aussies) were a source of ammonia, and every surface in the tank is now covered with ammonia eating bacteria. But you are limited as to how much ammonia the bacteria living on the gravel and rocks can process. Enough for a couple of yabbies or a small goldfish yes, but not for a whole tankload of fish. The cycle bacteria will set up shop any place there is water flow, oxygen and ammonia. A proper filter just gives them the ideal home. But lacking a proper filter, some bacteria will live on anyting in any established tank. They just cant support as many fish as the zillions living in a cycled filter. Ian