What does it mean if my fish wraps itself around the heater?

I received this query recently:

Hi Dr Loh,

I hope this message finds you well.

I was hoping you could offer some advice on recent behavioural changes with my Betta fish. I have JJ for 18 months now and 2 weeks ago I upgraded his 5 litre bowl to an 18 litre bowl with a heater. Since then his whole eating pattern has changed and he has lost his routine. He used come straight up for his food morning and night but now he barely eats at all. I also notice that since putting a heater in with him he hugs it a lot and I’m worried he might burn himself.
Is this behaviour something I should be concerned about?

Kind regards



My response:

Yes, there is certainly a risk of him burning himself. Why does he hug the heater? This is because he’s a tropical fish and is feeling cold, needing to be near the heater to feel the warmth. It is likely that the heater is not performing efficiently to warm the entire aquarium evenly. The water temperature should be 24-28 degrees Celsius. One way of rectifying the issue is to ensure good water circulation around the heater. Some ways include placing air stones beneath the heater, positioning the heater at an angle or near the water filter outlet. If he continues to wrap himself around the heater, it might be a behavioural thing. You can purchase or make your own fenestrated heater cover to prevent fish coming into direct contact with the heating elements.


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