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Dorsal Spot of Bantam Sunfish


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#1 centrarchid

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Posted 01 April 2017 - 07:08 PM

It is the time of year I setup home aquarium to breed Bantam Sunfish.  This round the tank is larger around 125 gallons so able to keep a range of sizes in addition to multiple males and females.  This go males are all small age-1 as are the females.  Males will be the smallest I have attempted to breed but they seem to be getting into the mood without trouble.  Largest male pushing 1.25 inches and before in the mood had dorsal spot of juveniles and females.  As males start getting into breeding mode they periodically loose the spot but when relaxed the spot is restored.  Females can drop spot while actually spawning.

 

I am wondering what the spot does for the fish.  With really small Bantams is may play the same signalling role it has with Bluegill and Green Sunfish.  Tanks I have been using may causing a container effecting masking behaviors the spot might be important for.


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#2 centrarchid

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Posted 02 April 2017 - 08:28 AM

All are starting to vent present with males starting to restrict movements to areas they are driving other fish away from.  Must get on stick and put nest bowls in place.  Males have more reddish markings on vertical fins while females are getting silvery.  Females must be transferring more pigment to ovaries


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#3 centrarchid

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Posted 02 April 2017 - 09:36 PM

Dorsal spot may have similar role to dorsal spot in "bratty" bluegill.  When feed is concentrated in space and time make defense of feeding location impractical, then the bantams come together and feed.  When feed not so concentrated they disperse to the locations that seem to represent tight feeding ranges that they do defend with frequent displays.  The feeding ranges of fish with spots very tight.  Males liking spots move about more and are starting display to each other more on left side of tank.  That is where the nesting area I think will be.  Males starting to show pearlescence and females even betting bars from time to time.  Both sexes adopt bar through eye when really aroused.  Smaller bantams have not trouble threatening larger bantams of territories.  Other sunfishes respect rank based on size more.


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#4 Michael Wolfe

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Posted 03 April 2017 - 10:44 AM

I'm loving this thread. I certainly don't have anything to add, but I am enjoying the learnings.
Either write something worth reading or do something worth writing. - Benjamin Franklin

#5 gerald

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Posted 03 April 2017 - 04:39 PM

If i'm understanding your meaning, dorsal spot in Lepomis means "willing to be sociable, it's OK to get close to me", and fading of dorsal spot means "keep your distance from me" ... have i got that right ?


Gerald Pottern
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Hangin' on the Neuse
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#6 centrarchid

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Posted 03 April 2017 - 08:32 PM

With Bantams I am watching, spots indicative of defending small territories.  .Spot seems also to be default coloration for females.  With smaller adult males still capable of showing spots, the spot is dropped when aggression get intense or trying to show rank over a larger area.  Bluegill showing spots as brats also defend a smaller territory but drop spots usually when moving away from defended area.  Spot on dorsal with Bluegill in a shoal may still serve as a spacing mechanism.


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#7 JasonL

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Posted 03 April 2017 - 10:29 PM

Interesting thread.

I have had a couple bantams in my 110 gallon tank for over a year that are now in the 2-2.5 inch range. They have never darkened up, displayed or lost their dorsal spot. Is is safe to presume they are most likely females?

#8 centrarchid

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Posted 04 April 2017 - 05:49 AM

Yes, males loose dorsal spot before 2" with stock I have.  My males no with red eyes while eyes of females have brown. The silvery look of females does not stand out unless males of similar size also present.


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#9 centrarchid

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Posted 04 April 2017 - 07:19 AM

Either feeding regimen is disrupting territorial behavior or their is a diel pattern to it like with chickens.  Sex ratio I am now a little more solid on now.  Four females, three males with one being very small but sassy, and a juvenile that hold a very tight territory like some lake dwelling cichlids are prone to.  My 5-year old son is also able to sex the Bantams accurately but is not able to relate to me how he does it.


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