Does phosphate cause stunting?

So, is the question: Does the phosphate cause the stunting, or is it adverse conditions, such as overstocking, that causes stunting with a concomitant increase in phosphate?

Vertebrates are pretty good at regulating their internal milieu (any points for fancy words?). If I were to hazard a guess, I'd say the phosphate inside a fish does not reflect the phosphate outside.

Since phosphate is highly charged, it won't easily pass through membranes, so it would be relatively easy to keep out of the body. It would have to be transported into the fish actively in the gills.

If I remember, I'll have a look in my fish physiology book at home tonight.

True, but, if I recall correctly, many cells use the electrical potential difference between the inside and outside of the cell as the driving force for many active transport systems, or would that be passive transport since no ATP is required?

Excess negative charges outside the cell would alter this potential, changing the effectiveness of the transport mechanism. Just a shot in the dark here, btw. If the cells were less effective, or had to resort to energy requiring pumps, then perhaps the extra energy required for cell homeostasis would result in less energy devoted to growth.

This could also be the case in cells regulating their internal PO4 content, with a steeper up-concentration gradient to work against.

But again, PO4 could simply be a measurable proxy for other organics more prevalent in overstocked tanks that could cause unhealthy conditions, reducing growth rates...

Molecular Biology aside, it seems reasonable that the Ca++ & PO4-- interactions would increase with PO4 concs. With Ca more difficult to obtain for bone development, nerve and muscle control, this too could reduce growth, I think.

Man it's been a long time since my last bio class...

I think my initial post was unclear. I don't think the phosphate will get into the fish. It has to get past the gill membranes first, and won't do that easily as a highly charged molecule.

Coral cells can't control the solutions their cells are in, fish can.

If Ca levels were to change from their usual 10[-4] M outside and 10[-7] M inside cells, it wouldn't just stunt the fishes' growth. It would kill them outright.

I'd like to hear more.

Where is it accumulating? At what levels?

Hey don't look at me, I was just applying knowledge to a question. Mogurnda's the biology expert here. But I will check it out in some of the biochem texts I've got at home.

Maybe I'll run it by some people in the fiance or some people in her biochem lab. I doubt I'll find the answer, they're all gene people, but there are some smart cookies so you never know...