I do believe even though a tanks water may be harder than in nature, in a closed
system these levels drop rapidly thus need to be replenished be it by whatever
means necessary. Shell grit is far to slow unless you use a fair amount. I have
tested water with shell grit days after addition with little change or at least
less than 17.9 ppm. I do use ro water with addition of "normal" water to achieve
a 100 ppm base, some some fish do fine, others do not therefore the block goes
in. It could be possible that in certain situations the calcium could be
consumed as fast as it becomes available from the shell grit but when you are
dealing with the numbers of fish as I do in one fry tank the coral/shell grit
just doesnt cut it. I typically raise between 30 and 150 fish in a ten gallon
tank to the size of 2.5 cm or 1 inch. With the numerous water changes that are
required for this quanity and the load on the calcium, it is depleated so
rapidly that the reef blocks are the only easy suitable answer for me and It
works extremely well so if it aint' broke dont fix it is the way I see it. I am
not sure that there is a majority of hobby Rainbowfish breeders that breed as
numerious quanities as I do so my practices may not apply to them. When I get
some eggs from you good fellas in Oz It is an oppertunity that usually comes
around once per species and if I am going to ensure the establishment of that
species I must raise a couple hundred or so and get them to as many people as
possible to get a strong foothold of that fish here in the U.S. 30 fish just
wont do it.
On the other hand...Let us try to keep the fish as pure and geniticly diverse as
possible. Albinos are oscars and hybrids are discus. Lets let Rainbowfish be
RAINBOWFISH. The fish here in the U.S. available commercially are pathetic and I
dont believe diet is the cause because their nasty colors breed true. If you
line breed fish for 50 generations that originated from say a pair, If you dont
practice good genitic control you end up with MUCK!
On the subject of sex ratios I have probably been as near to 50/50 as I would
like to be. I generally trade fish in pairs and when I get to the last 15 or so
I still may have a few pairs left and that is from a group of around 100 on the
average. This wasnt allways the case. When I was starting to learn about the
fish anything went and the ratios were sometimes disasterous. I finally figgured
out that too hard of water say at the 400+ range was the culprit. It was not
uncommon for me to have 90% males or vise versa. Different species reacted
differently. Pygmaea was the worst. I would get all males or all females if the
water was too soft or to hard but like goldielocks you need to get them j-u-s-t
r-i-g-h-t and 250 ppm is my recipe. However, I have a suspicion that the
hardness isnt allways the culprit, I do not yet know what or where to look for
an answer to this but in nature the ratios are not equal and in different
waterways I think I have read that there were some large swings in ratios. I
doubt that the lessor occuring sex would be classified as the dumber of the two
and I dont think the predators Know the difference between males and females. I
would like to hear some ideas on this note. (his should be a good oppertunity
for my Yank friend Mr. Unmack :-) )
These observations are purely my own and any objections call 1-800-LACTOSE ;-)
Roy Boy
credentials here