<<P is limiting because bones are made of Calcium Phosphate I believe.
Thus you need a supply of both for it to work.
Personally I think the addition of some shell grit probably is beneficial
and I typically use it. I think Roys blocks are most likely better
again. I don't really think, or are yet to be convinced that it is
benefical due to adding calcium except perhaps in soft water. I think it
probably has other small effects such as buffering pH and just adding a
few other little "bits" to the water. Certainly, I don't think there is
any danger in adding it either. I just feel that if we can figure out
the requirements of the fry better we will likewise do better in raising
them rather than just plodding along in the dark>>
Now we are really getting somewhere with this thread. It seems that the problem may really be -
!. maintenance oif basic water quality for the fry with buffering systems most important at this level because of the high metabolic astivity goingon - fry crowing, uneaten food etc so the calcium+ is the most significant of the buffering systems
2. some species (especially in soft water set-ups) will need calcium for bone development as they can absorb some from the water through their gills (? and swallowing some) but Phosphorus needs to be there also in suficient amounts otherwise the fish can
't use the calcium no matter how much is there.
3.Water changes will help most of these as long as the water contains enough Ca but perhaps we should be adding a phosphate buffering system concurrently to get better results.
4. There is still the problem of ?pH or perhaps Ca levels affecting sex ratios in the fry.
<< how
much buffering do a few pieces of shell grit provide? Not much I bet
but I've never tested it and it may just be enough in those first few
days>>
I guess it all depends on how many fry we (each of us) are trying to raise from each batch.
. << One of the things that has always bothered me a little bit is we
tend to (from what I have seen) mostly raise bows on a carnivorous diet
(vinegar eels, brine shrimp etc) with very little plant material.>>
There is no doubt that fish nutrition (human nutrition also for that matter) is one of the neglected frontiers - despite all the literature available. The big problem seems to be no studies on normal nutrition or on optimal nutrition for good health and l
ingevity. Most of the work is aimed at the "intensive" side of things so is domionated by concepts such as limiting factors.
<< The
Americans mostly use APR which may help the situation a bit. What do
people suggest as possible "green" fry foods? Obviously there is green
water,>>
Peter you are living in the" heartland" - the "home of Spirulina". It is available in fine powdered form comparable to APR and it should be a "simple" matter of determining the correct proportions of SP to APR for each species. Then we only neeed to give
the live food (BS nauplii, micro worms etc) for variety and a few micronutrients.
Perhaps Roy's "lactulose" could help fix your final comment :-)
Bruce Hansen ANGFA