A rapid change in temperature can affect betta fish in a major way. Sudden drop or an increase may result in a change on its behavoiral and physiological state. This is termed as 'cold shock'.

A cold shock stress happens when a fish has been acclimated in a specific range of temperatures and suddenly exposed to a rapid decrease in temperature.
If you are a beginner in taking care of fish, there are some methods you can do to prevent cold shock stress. But first we have to know how to identify if your pet is suffering one.

A common sign for temperature shock is lethargy. Unlike mammals, fish are cold-blooded and can only absorb warmth from the water.

They will stop moving. If the water is too cold, it will be difficult for them to swim around so they will avoid swimming around the cold water.

You find them resting at the bottom of the tank. Because it is difficult for them to swim around, you will find them just resting at the bottom. They find it hard to swim for the surface or they do not have energy to do this.

An extremely low temperature may lead your fish into coma. This is a red flag already so must take immediate action.

There is also hot temeprature shock which isnot also good for fish.

When you see your fish breathing at the surface, its normal and may seem to look natural. But notice if your fish is breathing rapidly. This could mean that your water is too warm for them.

Warm water don't contain much water than cold water does, so fish tend to go to the surface for oxygen. They will stick there and when you notice rhis, you have to check the temperature.

Also, when you notice your fish swimming quickly, while it could be a normal sign, erratic movements could stress out the fish. Warm water keeps them heated up and tend to be energetic but this is not a good sign anymore.

Checking the temperature is a necessary task. The weather could contribute to this change in their environment. When it is cold, you should put up a warm blanket around the tank or cover the lid for the heat to be sealed in. When it is hot, you can put right amount of ice cubes into it.

Do this also before you bring in back your fish in after a water change routine. Personally, when I change water, I put my betta in a glass bottle and let it float on the new water. That way, they can adapt to their new water temperature and not shock them. I let is stay there for 10 minutes, then I pour them in to their newly changed water tanks. I put also a pinch of salt too to prevent diseases and Indian Almond leaf.

Taking care of fish for me is therapeutic and a stress reliever, and by just looking at them swimming carefree makes me happy.