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TROPICAL

Could a scented candle be a danger to my fish?

Please could you tell me whether a scented candle might affect my fish? I’ve just had four fish die on me - two Bleeding heart tetras and two Yoyo loaches. I tested the water and the results were okay, but I carried out a 25% water change anyway. The other fish still looked unhappy, however, so I’ve added charcoal to the filter in the hope that it will remove anything nasty that might still be in the water. Please could you advise?

BRIAN SADLER, VIA EMAIL

NEALE SAYS: Without knowing exactly what was in the candle, it’s impossible to know for sure what happened here. However, your response - substantial water changes and the use of activated carbon - is spot-on, and if you do some more water changes over the next few days, the remaining fish should recover. If you add a little extra aeration, that’ll help as well, especially if the toxin affects the way that blood carries oxygen.

Broadly speaking, anything you can smell in the air has to be considered a potential risk - whether scented candles, room freshener, cleaning products, paint, or anything else giving off airborne chemicals. With that said, many such products are perfectly safe, and described as being ‘pet safe’ or low VOC/VOC-free (where the VOC part refers to volatile organic compounds, the most like chemicals to cause problems for your fish).

If you use any products with an airborne component - perhaps an odour of some sort, or else something you spray into the air - you need to be more circumspect. I don’t worry too much about using a bit of furniture polish in the same room as my fish tank, but if I was doing something like painting the walls, I’d be more cautious. And if it was something I didn’t need to do at all, like use an air freshener or scented candle, I’d simply use those items in another room.

I think you’re unlucky, more than anything else, and regular candles certainly don’t cause fish to die. I think that it was highly likely something was a bit off with that particular brand or scent. But lesson learned, I suppose, and I hope the remaining fish recover quickly and you can get back to enjoying a happy and healthy aquarium.

Scented candles may be harmful.

MARINE

Can I stop my clowns from jumping?

I have a marine tank that holds approximately 120 l. It has a cover glass which sits on top of some plastic clips, allowing a small gap of about 5mm around all the sides. There is also a feeding hole in the glass. I have now lost two clownfish out of this tank, finding them dried out on the floor in the morning. I lost the first one about three weeks after I added a pair. The replacement fish - a male I think - lasted less than a week. Is something spooking them at night and if so what might it be? There’s only a Cleaner shrimp and some reef hermits in the tank with a few frags, as I’m still stocking. Would it hurt to plug all the gaps? Is this sort of behaviour normal for clownfish? The tank has been set up since the end of October. I’m not sure whether to risk adding another clown or any other fish to this tank unless I know what’s wrong.

PAUL BAKER, VIA EMAIL

JEREMY REPLIES: Unfortunately, tank bred clownfish jump out all the time, and through the smallest of gaps.