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If I start experimenting with metals for aquariums, how can I detect that the metal is causing the problems? I want to clearly identify the metal toxicity from wrong pH, wrong temperature, bad filtration, infections...

  • Can you better describe what you mean by experimenting with metals? Also is this a saltwater or freshwater environment? Generally you want to keep metals out of aquariums, saltwater especially, if possible.
    – Jestep
    Sep 25, 2020 at 20:17

2 Answers 2


I don't think it is possible to easily know this for sure, both because of the often non-specific symptoms of toxic metal poisoning and the fact that an aquarium is a complex biological system of interconnected vessels which could be all simultaneously affected by their toxic action and thus present ambiguous results.

Mentioned diagnosis difficulty is also the case in humans; even though humans, in contrast to fish, could describe their perceived subjective symptoms themselves, accurate diagnosis of metal poisoning requires laboratory analysis of blood, hair or tissue samples.

For example it might be close to impossible to immediately differentiate metal poisoning from ammonia or nitrite poisoning, because a lot of metals, especially heavy metals, are also extremely toxic to microorganisms, much more so than to fish. If the toxic metal presence kills beneficial flora in the filter media, it will result in ammonia and nitrite poisoning symptoms, but without knowing the context it might be impossible to tell that it was the metal that caused this in the first place.

However, in the market there are various test kits for detecting and measuring the amount of dissolved metals in the water, which are in principle similar to ammonia, nitrite and nitrate test kits; they could be either specific and aimed for a single metal, or be all-in-one test kits sensitive to the presence of multiple elements. It might be viable to use such test kit in case you suspect metal poisoning.

An article about this on theaquariumwiki.com lists various symptoms of toxic metal poisoning, but as you could see they aren't exactly specific:

Acute poisoning - leading quickly to death:

  • Gasping at the surface or lying on the substrate
  • Shimmering
  • Uncontrolled swimming
  • Glazed or non-moving eyes

Chronic poisoning - slow death:

  • Loss of appetite
  • Breathing more rapidly
  • Shimmering
  • More likely to catch fungus and bacterial disease due to damaged immune system
  • Growth deformities

Why would metals be a problem in an aquarium ? Just don't put in anything with copper. That is pretty easy as copper alloys are red /yellow color except monel which is not common and expensive. Copper is toxic that is one reason is is used on ships to reduce fouling by organisms. For there to be a problem the metal must dissolve or corrode to put ions in the water. I can promise you from experience that iron, stainless steel, nickel alloys, lead , aluminum are not a problem. X-ray fluorescence would be the cheapest way to detect metals; I think today you could get a cheap unit for a few thousand dollars (US).

  • 1
    I would like to know why lead will not be a problem? Dont lead usually cause lead poisoning when immersed in water for longer period?
    – gfdsal
    Sep 26, 2020 at 11:01
  • 1
    @gfdsal Actually you are correct, that's the exact reason why cities avoid installing lead pipes for water transport. Lead forms passivation layer which slows down its leaching in the water, but certain substances could and will slowly dissolve this layer as well, especially in the presence of oxygen and acidic conditions, and especially in the saltwater aquarium. Using lead elements in aquarium will most probably result in no apparent ill effects, but is definitely NOT safe.
    – lila
    Sep 26, 2020 at 13:04
  • Lead was the premium choice for water pipes for 2000 years, that is why plumbers are named after lead ( Pb = plumbum). I have used lead bands to hold down plants forever. Ever since I bought my first bunch of anacharis held together with lead bands from the dime store . And have many lead bands in my tanks today to hold down plants. I did not use lead bands in my salt tanks because the various calurpas will not root. Sep 26, 2020 at 16:27
  • 1
    It's true that lead was used for water pipes - but that's not because it's safe, but because it's soft, malleable, easy to machine and shape into pipes, has low melting point and is cheap. It was important in the era of Roman Empire 2000 years ago that they didn't have today's technology and tools to make pipes from other, safer materials. Here is a recent (2014) case of lead leaching from aging pipes into drinking water. I believe the amount leaching into aquarium from lead weights is negligible, but I just personally would avoid using it.
    – lila
    Sep 26, 2020 at 20:43

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