I have a small garden pond (1x1m and a foot deep) that is surrounded by plants that bear red/orange flowers/fruits. When the chili plant became mature, the chili peppers just fell off into the pond where they started rotting.

There are 3 types of aquatic plants in the pond that provide oxygen. It always rains here so there's no need to have a direct source of fresh water. I have guppies, swordtails and mollies that have been there for two years already. There are unwanted snails and frogs too. There haven't been any dead fishes until the chili pepper started rotting in the pond. Did the chili kill my pond fishes?

3 Answers 3


Water movement is much more effective than plants for the oxygenation of water. Your live bearers will overpopulate a small pond in less than a season. Water movement can overcome the negative affect of the organic decomposition.

I just cleaned my small pond, which is has a surface area of 10' x 5' and 3' deep (3 x 1.5 m on surface and 91 cm in depth) after a few years it had nearly a foot (30 cm) of needles, leaves, pine cones , branches. etc. The fish were fine in that mess (about 100 giant danios and 2 large koi) because of water movement.

So I think your fish ran out of oxygen because of overcrowding and decomposition of plant material. An air pump/and/or a filter pump is needed.


I am no expert but my grandparents love their fish and they always day fish need clean water to roam in so maybe you should filter out the chillies so they do not consume them also check all aspects and not just one. (Forgive me if this is info is incomplete or wrong I am just giving you my aspect)


Well, all three of those types of fish are brackish water fish, which means they tolerate and even prefer hard salty water up to a point. If you have organic material rotting in the pond, it could quite possibly lower the pH below what these fish can handle.

It is always recommended to keep detritus from accumulating in ponds, Especially small ones like yours because the rotting can also consume a great deal of oxygen.

So there you have two possibilities as to why your fish may have died.

One more thing. Where are you? If you are in the summer time right now, the added heat also reduces the amount of oxygen the water can keep in solution. Cold water can hold more oxygen than warm water, and the summer time is always a dangerous time for fish because the added heat not only stresses some fish, but also makes less oxygen available to them.

  • Those fish are freshwater fish. None of them require brackish water.
    – Rémi
    Commented Dec 18, 2015 at 20:47
  • 1
    Guppies and mollies, at least, do well in brackish water. But I'm not sure that the salt/pH/hardness are described correctly here. That said, the decomposition could quickly cause such a small pond to go eutrophic and kill the fish. Also those are very hot peppers. I find it easy to believe that the capsaicin destroyed mucous membranes and gill tissue.
    – That Idiot
    Commented Dec 21, 2015 at 21:23

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