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Red-tailed Sharks Housed in Groups

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centrarchid

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Thanks for access to the PDF. Information provided on behavior. Sampling method was not indicated. In my experience habits like that yielding the single fish are difficult to get representative samples from by seine or electrofishing, especially with benthic oriented species that like to retreat down between rocks. Some sort of under water video recording gear might have been more sensitive to Red-tailed Sharks.
 
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The Red-tailed Shark Minnows (RTSM) are eating at algae on aquarium much of the time but I cannot see changes in coverage even though the fish are clearly ingesting it. I started cleaning the front glass only and all fish quickly increased gut fill.

Largest fish appears to be female based on how abdomen is distended and orange eye coloration. My eye-coloration assumption based on other species with similar eye color where the change coincides with sexual maturity. The female is a little over 2.5 inches so well under maximum size.' If correct, then I know someone that has a male pushing 4".
 

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Fish raised to spawn are injected by syringe with hormones. I saw an article in one of the Fish magazines 30 years ago about getting them to spawn. Pretty sure males and females were kept separate and rainwater..well,its best I can remember. I think a high quality Red Tail is one of the most attractive fish on Earth...I just can't handle the constant never ending aggravation they give tankmates. Almost always no damage..it just ruins the feel of what I want.
 
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I have hormones and delivery system. Outdoor culture tanks get run off from barn roof.
 
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Another color variation that may be related to sexual maturation. All fish at time of purchase had smokey gray pectoral fins. The largest fish pushing 3 inches now has reddish pectoral fins and second largest fish that is about 2.25 inches is also getting a reddish cast to pectoral fins.
 
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The fish are exhibiting a behavioral pattern that repeats. Most of time they have little home ranges where similar sized fish do not overlap and there is a clear size correlated hierarchy. Then they all come together and do a bout of displays that last a minute or so before the group disperses back to the previous arrangement. The is repeated at irregular intervals that are not shorter than 20 minutes or so.

Displays involve fish getting black contrasting more strongly with reddish tails. Dorsal, anal and pelvic fins are extended to them max.
 
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Sharks starting to show strong iridescent green on back fins. Three largest are growing about 0.5 inches per month. Pretty fast for a minnow that eats mostly greens.
 
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I have seen red tailed sharks at Busch gardens here in Florida and they get huge!!
How big is huge? Largest I have seen to date has been a little over 5 inches. The color on those was washed out. Best breeding size I think will be well below that.
 
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I have just set aside a 2,500 gallon fiberglass tank located on east side of building that will be used to condition fish for breeding. Currently it is being managed for Pirate Perch that will be removed by latter part of April. Volume is being fertilized with chicken manure and provided a stocking of mixed zooplankton species. The zooplankton will likely crash by time Red-tailed Sharks are introduced. Diatomaceous Earth and additional chicken manure will be added to promote diatoms the sharks can consume.

Based on growth rates exhibited in an aquarium, Red-tailed Sharks can reach maturity by 1 year of age. I assume that growth rate can be bettered in an outdoor setting where quality graze is not limiting.
 
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During the growth and conditioning phase I am trying to promote attached algae / diatoms in the tank housing the Red-tailed Sharks. The sharks have been eating a lot of the aufwuchs maintaining big bellies and rapid growth. Last night the light was turned off resulting in a large number of snails coming up to graze much of the aufwuchs leaving the sharks with less to eat today. Lights will be kept on from this point forward to keep snails down.
 
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Sharks appear able to switch back and forth between a shoal with pecking order to territorial. They have a suite of behaviors enabling the former social organization. The immature (black pectoral fins) fish are in shoal mode most often.
 
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New phone so better pictures. Sort of.

Snail abundance became abundant when lights turned. Bad as they consumed a lot of aufwuchs fish need.
IMG_2020-03-07_06-55-22.jpeg

Red-tailed Sharks are growing fast. Lost on to cichlids. Others looking real good.
IMG_2020-03-22_20-37-57.jpeg
IMG_2020-03-22_20-38-36.jpeg
IMG_2020-03-22_20-38-39.jpeg
 
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