Hello Hive,
Good day, 
In today’s post, I’ll be sharing the different implications of why bubbles may build up in a fish fingerlings tank.
From my experience working at the hatchery with my brother, I had always believed that bubbles on the water surface in a fish tank were a bad sign. However, yesterday evening, while strolling around the compound, I passed by the hatchery to check on the fish and noticed numerous bubbles in the tank with the fingerlings. Immediately, I called my brother’s attention.
When he got to the hatchery, he laughed and said, “You scared me, these are good bubbles.” That led me to ask what the difference was, and that is precisely what I’ll be sharing today.
According to him, there are good bubbles and bad bubbles in a fish tank, especially when raising fingerlings.
Good Bubbles
Good bubbles are usually formed at the water surface when inlet pipes from a flow-through system drop water into the tank. This is a positive sign, as it indicates that the water quality is good and oxygen circulation is strong. This helps the fish breathe better and supports their overall growth.
Another reason for good bubbles is the fish's activity level. Our fingerlings are now seven weeks old, and their energy has doubled. They make little dives, swim around actively, and generally behave like busy bodies. 😂 Because of their increased activity, they require higher water levels and improved flow-through to give them more space and oxygen. The bubbles caused by their movement are normal and burst quickly.
Bad Bubbles
On the other hand, bad bubbles usually indicate a problem with the water. This can be a sign of:
Low oxygen levels, often caused by overcrowding
High ammonia build-up (I discussed ammonia in detail in an earlier post) @wewarriors-28/why-ammonia-builds-up-in
Overfeeding, which leads to excess waste
Poor water flow-through or stagnant water
These bubbles often appear foamy, do not burst easily, and stay longer on the water surface.
Another warning sign is when bubbles stick to the bodies of the fingerlings. This can indicate ammonia burning their gills, which is dangerous because they breathe through their gills. If not corrected, this can lead to high mortality.
How to Differentiate Good and Bad Bubbles
Here’s what to look out for:
Good Bubbles
From when fresh water drops into the tank through the flow-through system
Burst quickly and do not stay long
Form due to fish activity, and also disappear quickly
Bad Bubbles
Look foamy or thick
Stay longer on the water surface
Do not burst easily
May stick to the fish, indicating stress or ammonia irritation
What to Do If You Notice Bad Bubbles
Increase the flow-through system immediately to improve oxygen circulation and dilute waste.
Check for other possible issues:
Infections → you may need to treat the water
Overstocking → reduce the number of fingerlings in the tank
Thankfully, there was no cause for alarm in our tank yesterday. The bubbles turned out to be the good ones, just clean water dropping in, and our fingerlings having a great time. They are always more active at night, which explains why they created even more bubbles.
Thanks for passing by. Cheers and have a great day.