The signs shows up before symptoms do. While sitting at surface, the Molly suddenly stop moving. It then rapidly flap its fins back and forth.
It is almost as if you can see the fish shuddering. It is almost like some kind of uncoordinated dance or nervous tic. And since filter is on and the tank water are clear, you might not be overly concerned right away.
But more often than not, that shimmy is no simple quirk off the fish’s personality. It is a distress signal expressed through body language. If you ignore it, it typically result in even greater difficultie down the line.
Understanding Why Mollies Shimmy and Water Quality
What Fish Shimmying Means
In the aquarium hobby, most beginners think that clear water are healthy water. This thinking is hazardous. Livebearing mollies is a very hardy species.
However, mollies can be picky about certain chemical imbalances. In nature, they inhabit either saltwater or brackish waters. Their physiological makeup handles different parameters then purely freshwater fish.
If there’s something amiss with your water, the fish will let you know (just look at the fish). It’ll shimmer. Once you understand the root cause of such behavior, it change how you maintain your tanks.
Why Mollies Are Sensitive to Water Chemistry
You stop thinking about removing detritus from the glass and start watching water chemistry, things you don’t see. If you are familiar with what you’re looking for, you can catch early warning signs without expensive testing kits, and you have a detection tool available daily in the form of the shimmy. Recognizing the behavior as a reaction to stress (rather than some random habit) is key.
Ammonia and Nitrite Poisoning
What causes a fish to shimmy? The most common reason for shimmy are dirty water that contain ammonia or nitrites. These are toxins that irritates the fish’s skin and gills, which is similar to having mild acid rain on your own skin.
It burns! So the fish will swim as fast as he can to get out of it. You may not notice the odor, or the cloudiness in water, but the water chemistry isn’t good.
Ammonia comes from decaying plants, uneaten food, or fish waste. So if you’ve fed too much or just introduced some new fish, then this is probably the issue. The only way to know for sure is to test the water as soon as you notice the fish shimmying.
Low Water Hardness and Osmotic Stress
Low water hardness are another common trigger. Generally speaking, mollies prefers a harder water with a higher pH, such as 7.5-8.5. If your tap water isn’t naturaly hard, or if you are using distilled water without adding minerals back in, it will cause osmotic stress for the molly.
The body will struggle to regulate its water and salt levels, causing the stress to look like a shaky, nervous swim. This is especially prevalent in areas with soft water, since the tap water lack sufficient amounts of magnesium and calcium. While adding a pinch of aquarium salt may improve their condition, it’s best in the long term to address the underlying issue of low hardness.
Temperature Fluctuations and Metabolic Stress
Another important factor in Molly behavior are water temperature changes. Mollies like warm water, ranging from 75-82 degrees Fahrenheit. When your room cools off or the heater break, stress levels increases and the fish will become sluggish.
While cold water does hold more oxygen, its metabolic rate and immune response is slowed as well. A healthy fish exposed to sudden temperature change may be more vulnerable to disease. Make sure your heater is functioning properly and that tank is not sitting next to drafts from vents or drafty windows.
Disease Signs and Quarantine Protocols
Perfect isn’t necessary…stability is. Another potential mimic of water quality problems are disease. Clamped fins, white spots, and/or body discolorations could all be signs of ich, fin rot, or other bacterial infections.
In this case, if the water checks out okay and there’s still shimmying, medical intervention may be required. Treating a disease isolated from the rest of the population is relatively simple; treating an outbreak after it has spread throughout your community are far more difficult. To prevent possible pathogens from infecting other tank inhabitant, quarantine the sick fish.
Preventative Maintenance for Healthy Tanks
It’s always better to prevent rather than to cure, the adage holds true for aquaria as well. You can maintain stable parameters and keep toxins at bay with regular partial water changes. Feed only appropriate amounts so there isn’t as much waste build up.
Add plants that assist in absorbing nitrates to help support the biological filtration system. Finally, observe your fish regularly so that if something doesn’t seem right, you can catch it before it turns into a crisis. Fins flickering is a way to start a conversation.
Listening to what the fish are saying keeps your tank healthy.
