I used to have a lot of dirt spawning killifish and had boxes with bags of dirt
incubating in them. Dates for each bag were marked on the outside and on the
calendar so I wouldn't forget to take them out on time and hatch them. Each
species has it's own incubation time, you learned this by trial and error or by
belonging to the AKA and finding someone who could help you along. One thing
that was repeatedly obvious, if you waited too long the fish came out as
belly-sliders, sometimes the whole population. As started in other threads
careful observation would suggest when it was time to add water. The eyes are
really developed and you can see the fry moving inside the egg. Thank god that
we don't have to incubate bows/blue-eyes in dirt as it isn't real easy to find
them always. For cyanodorsalis and Ross River signifers I use the same sort of
observations. I had written a thread many months ago on "forcing eggs" so I
don't want to really repeat it here. But the main thrust is to change the
environment of the eggs. If I am tray hatching, surely some of the water has
evaporated so that the salinity has increased. Change it, most of the time to
warmer temperatures, probably about 81 F. Eggs that are ready to hatch will
often do so. This may also be the same observation that Mach is seeing when he
changes his water in the parent's tank and then observes all of the fry...OR it
may be the change in pressure...
I have observed that the bottom of the cyanodorsalis tank can be littered with
"eyes" in the algae tufts waiting to hatch. I come thru rather roughly with a
siphon and while doing a (40%) water change siphon eggs and dirt thru a net.
The eggs and dirt are dumped into a shallow tray with the same water. Within a
half hour I'll get a lot of the collected eggs to start hatching. By the next
day I'll also do a water change on the dirt and more will hatch. If I get lazy
and don't do that water change it seems like many of them do not hatch. If it
ends up being a week later then I notice belly sliders. My take on it was they
were ready to hatch but I didn't give them the extra push they needed to
emerge. They ended up over-developed which from my killifish experience
produces belly sliders. I think that the pressure difference coming from the
bottom of an 18 inch deep tank to a tray only a few inches in depth is enough
of a change to help with the hatching. I have also put "tray eggs", that is,
eggs that have eyed up in a shallow tray, into a vial
with a loose cap and dropped it into my deepest tank for an hour. The pressure
on the eggs is increased and sometimes fry hatch right then. Many often hatch
when the vial is decompressed, that is removed from the tank.
Blowing CO2 into the water can cause a pH change in soft water. I sincerely
doubt that it is helping anything in 1/2 salt because of the buffering capacity
of the water. It was a good trick for hatching killifish but probably not so
useful for
bows, especially those in saltwater. A proper control would be to breath thru
an airline tubing into one vial and then just use an airpump to add air to the
second one to rule out
mechanical "tumbling" as the reason for hatching.
I think that the best way to avoid sliders in blue-eyes is to change the
hatching trays often, which produces an environmental change which induces
hatching to those that are ready. These same techniques also apply to
Telmatherina bondti - remember that "big signifer" you saw at Steve Polk's
Bruce???
Gary Lange
gwlange at STLNET.com
Rainbowfish Study Group of North America
http://home.stlnet.com/~gwlange/rainbowfish.index.html
----------
> From: Bruce Hansen <bhansen at ozemail.com.au>
> To: rainbowfish at pcug.org.au
> Subject: Re: [RML] Body Sliders
> Date: Thursday, June 04, 1998 5:46 PM
>
> Belly sliders are a common problem if you talk to Killie keepers but I
> cannot recall ever getting more than an occasional one and then only in
> "Poppondettas"
>
> I assumed it had something to do with prolonged incubation times.
>
> Regards,
> Bruce.