Fish changes the water quality in the aquarium Artificial feed added to the water has a great impact on both fish and water quality. Fish consume oxygen and release and excrete large amounts of chemicals such as: uric acid, nitrogen compounds, etc. Bacteria in the water break down most of these substances and convert them into minerals. Of course, a lot of oxygen is consumed in the process of decomposition. Slowly, the nitrate and phosphate levels in the water increase, while the carbonate hardness and pH value (PH) decrease. 水草改变水族箱的水质 蔓生的绿色植物，尤其是茎状植物在白天会消耗二氧化碳，而全天都会氧气和有机矿物质。 Photosynthesis releases oxygen and absorbs carbon dioxide during the day, resulting in an increase in the pH of the water and calcium carbonate precipitation on the leaves. Too much bait in the water will sometimes lead to the stagnation of plant growth. After the plant dies, the stored nutrients such as starch will be released into the water, resulting in an increase in the nutrients in the water and a sharp decrease in the oxygen content. 何谓水族箱中的生态平衡 很多人深信，只要在水族箱里放养一定的鱼和植物，水族箱内的生态便可永保平衡稳定。 In fact, this is not the case. If you do it that way, the ecology in the aquarium is definitely a tilt. 第一种可能是:鱼类占据了整个水族生态的优势。 They thrive on adequate nutrients (such as nitrates and phosphates), but the excess waste and toxins they excrete hinder plant growth. The turbid water quality has also contributed to the overgrowth of cyanobacteria, fungi and dinoflagellate algae. Finally, these algae overwhelm the plants and dominate the entire aquarium with fish. 第二种可能是:植物占了优势。 They consume most of the carbon dioxide, resulting in an increase in carbonic acid compounds, while the nutrients for fish and bacteria are greatly reduced, and finally the entire aquarium ecology is forced to stop growing. 为什么一开始妥善的按排，竟会演变成另人意象不到的结果呢？ That's because we shouldn't expect to maintain the ecological balance in the water once and for all. 如果水中的生态失衡，用肉眼是很容易辨识的，问题是那是以回天乏术了，所以，一有失衡的倾向时，就应该密切注意。 To test whether the water is dominant in fish, algae or plants, a titration test can be used. When the phosphate content in the water is higher than 0.1PPM and the nitrate content is higher than 30PPM, it means that fish is dominant; otherwise, it means that plants are dominant. 水中缺氧时，最明显的现象是早上发现鱼缸里漂浮着死鱼，或是鱼儿在水面痛苦的挣扎呼吸。 If there is a lack of carbon dioxide in the water, white calcium carbonate precipitates will be found on the leaves or bottom of plants, and the PH value of the water will also increase.