September 10, 2010
September 10, 2010
someone really needs to invent a robot that can do multiple water changes. :p
got that covered: the water changes in tanks are continuous due to a recirculating water system. The system would then have periodic automatic water changes during the day at the sump. Usually totaling 5-10%/day.
One thing I would like to know is why the addition of those meshed containers stimulates the fish to spawn?
The fish probably breed in the bare tanks, but they just eat the eggs quite efficiently.
On the other hand, about any different bottom is thought to attract their attention in contrast to the bare tank. Things used are a mesh bottom, vegetation) or in a lab fake vegetation), marbles (or gravel).
Other methods used to promote breeding:
- the males chase the females, putting little walls over the mesh helps the males corner the females
- a tank with a raise-able mesh bottom has been used to stimulate a lot of breeding in zebrafish by moving the bottom up until the fish are partly out the water. The fish breed a lot in a short time.
- certain substrate colors (red, most strongly, for lab bred zfish) can attract fish and they are more likely to breed there.
June 13, 2011
On the other hand, about any different bottom is thought to attract their attention in contrast to the bare tank.
This is the part I found intriguing in that the addition of the mesh caused the fish to rapidly enter what looks like a frenzy of spawning activity. New question - have you tried the substrate colour test with any other species?
September 10, 2010
The fish in the big tub were probably not bred much for a week or two prior to the making of the movie and where therefore ready to go. Fish for breeding are also fell fed.
Zebrafish also seem to like breeding in shallow water, which is the situation the mesh presented. This has been tested a lot. It is thought to be a remnant of their wild breeding behavior (in some lab strains, more than 90 generations removed from their ancestral fish farm stock) which is supposed to be in shallow water, often in vegetation.
WRT the color issue:
The color test was done by some people from Alabama if I remember properly. They presented it a zebrafish lab husbandry meeting I went to. They showed a movie of some fish in a clear plastic box, viewed from above, with a red vs. white color underneath. The fish very strongly preferred being over the red color. They liked some other colors, but not as much.
Its not clear that it should work on other sps. Seems like selection should strongly favor a preference for the appropriate substrate for that sps to lay in, which may well be a different color in particular cases.
There are also a handful of reports of different colors on incident light promoting conditioning and/or breeding in other species. At least one of these favors green (the opponent color of red in the way our retinas analysis colors, but not necessarily the fish do it). This seems like it might be conserved among a variety of sps.
Here is a reference (there are others also):
Light-emitting diode spectral sensitivity relationship with reproductive parameters and ovarian maturation in yellowtail damselfish, Chrysiptera parasema
have you tried the substrate colour test with any other species?
I have a tank of Danio jiantianensis set up with a particular area (on top of an egg box mesh) covered with some dark red, tank substrate, melted marble-like things. They have shown no preference for that area nor are they breeding for me right now. However, it is a tank with a rather dark bunch of stuff in it and fish like to hide in the (fake) vegetation. A different situation from a bunch of fish swimming in a well lit clear, mostly bare tank. I have not tried it on other sps, but its easy to do.
Occasionally aquaculture guys do tests like this for the things they culture. I have seen a talk on this at a meeting but don't remember the details. Its was undoubtedly a food fish. They have fish in tanks with the outsides painted different colors and compared something like growth, breeding, or maybe cortisol (indicative of stress (continuous stress is a major downer for fish)).
There could well be many studies on things like this, buried in obscure (to people like us) journals like the Journal of Photochemistry and Photobiology B: Biology. I would not have known about this unless someone had told be about it.
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