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Effects of ions like Ca and Mg etc. on skeletal developement


Active Member

Does anyone know any scientific study about the correlation between Apistogramma skeletal development and conductivity/TDS of water or specificly the calcium-ion content?
Or any such study of fish that naturally found in waters that have similar ion/conductivity related parameters to the natural water parameters for most Apistogramma spp.?

Or even information on how frequent there was any skeletal development problems with the fry of “big” breeders, when they kept using only RO water/rain water/low conductivity water?

I personally didn’t have any problems with the skeletal developement of Apistogramma, Copella or Betta fry when I only used RO water, but there are many Discus breeders who experience spine deformations when they don’t raise the conductivity of the grow-out tanks, so I wonder if I and some/many other breders are just lucky because we provide something(?) that prevents those deformations or if Apistogramma and some other genuses are adapted to develop in lower ion contents than fish such as discus.

I have not seen any studies about any species, so I mostly would like to see some, but even a bit more “breeder experience” could be helpful.


Mike Wise

Staff member
5 Year Member
I don't know of any such studies. Personally I doubt it is that important if the fish are fed properly. They get most of these elements from their food, not their water.


Well-Known Member
5 Year Member
Most of the scientific studies are on food-fish farming (trout, salmon, catfish, milkfish, tilapia, Lates, etc) and all of these grow faster and are more disease-resistant in moderately hard, ion-rich water. Pacu is the only fish I can think of that comes from mainly soft-water habitats and is farmed large-scale as a food fish. There might be info on optimal water parameters for pacu production in the aquaculture literature. But as Mike says, I suspect most soft-water fish rely primarily on diet for their minerals, rather than cellular uptake from the water. Let us know what you find - i'm interested.