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Cran's bullies spawning (New fry 11/12/11)


blueether

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Awesome!

They do like to choose the least visible place to spawn... mine seem to favour the back wall behind various logs at the moment. Somehow Snorkelboy(?) managed to get his spawning on TOP of a rock out in the open, lucky sod.

I love the colour the females go when spawning.

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They do like to choose the least visible place to spawn...
These two are right in the front corner so not too difficult to see. That cave had only been there for a day or two, I built it on Thur the 13th in the evening as the male was defending that corner, and by lunch on the 16th they were spawning in it.

The male is the one in my profile pic.

There is another Cran's guarding a cave right at the back, so far back I cant see if he has any eggs in there yet, most of the female Cran's and common are starting to look gravid as is what I think is a female giant (only has 6 spines on the first dorsal) (McQueen, 2010)

McQueen, S. (2010). The New Zealand Native Freshwater Aquarium. Palmerston North, New Zealand: Wet Sock.

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McQueen, S. (2010). The New Zealand Native Freshwater Aquarium. Palmerston North, New Zealand: Wet Sock.

:happy1: (excuse me....)

(Blueether, you in the middle of writing assignments?)

I had some uplands, two males two females, together in a tank and one of the boys ALWAYS scored the eggs of both females. The other guy was peeved. Then one time the girls both spawned in the other boy's nest. Oh man the first male became so insanely aggressive I nearly had to remove him!

The pictures below I took last week, two different upsidedown redfin females, both circa 9cm long. Both gravid - the orange bits are actually their ovaries! They have two ovaries, kinda long shapes down each side of the abdomen. The dark in the middle is intestine. I had never noticed this before (I guess most of my gravid females had been smaller and not upsidedown)

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2011_10_10Amberssite36Medium.jpg

Apparently gravid inanga look the same - males and females! But you can tell the difference by colour showing through the skin: females have orange ovaries whereas males have white testes.

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Cool! May you be inundated with littlies!
Just about lost the lot last night, the plumbing that waters the ferns/moss/etc above the tank came off and slowly pumped about 100l on to the floor in the front room :an!gry

(Blueether, you in the middle of writing assignments?)
No but the Mrs is
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Upland and Cran's bully fry don't need to go to sea, so they are easy to breed in aquaria.

Common bullies from a non-diadromous population (eg a lake) should also be easy to raise in freshwater because they have evolved to not go to sea. In this case the eggs will be big (2.5mm length), rather than the usual diadromous common bully egg size (1mm). That doesn't sound like much of a difference but when you see them it is really obvious!

Diadromous parents can't alter the physiology of the fry just because they can't reach the sea from their aquarium, this is an evolved trait with many changes required, including which season they breed in.

The reason for the egg-size difference betwen diadromous and non-diadromous fish is the difference in food availability and risk to fry. Females are only so big and can only invest a certain proportion of resources into reproduction, but the size and number of eggs can vary to suit the risk etc.

The diadromous lifecycle is fraught with risk, so it is better to spread that by having more eggs per clutch. The zooplankton in the sea that the fry feed off is at a much higher density than in freshwater, so it doesn't matter if they fry are small, there is plenty for them to eat so they will grow fast.

However for non-diadromous fish, the zooplankton in freshwater is less and larger, so the fry need to be bigger to be able to cope. There is also less risk to the fry, so it is better to have fewer larger fry to give them a head-start.

There isn't much zooplankton in streams, which is partly why so many of our fish are diadromous. Those that are not diadromous tend to have smaller adult sizes, which is related to not swimming in a sea of food when they were fry. (not that they are 'stunted', but rather evolved to suit this situation.) Where diadromous species have formed landlocked population it tends to involve rearing within lakes where the zooplankton levels are higher.

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:oops: thanks

Ok, the diadromous ones are further classified as 'obligate' and 'facultative'.

Obligate

Biology. restricted to a particular condition of life, as certain organisms that can survive only in the absence of oxygen: obligate anaerobe (opposed to facultative).

So these guys MUST go to sea.

Redfin, bluegill, giant bullies

Facultative

Biology. having the capacity to live under more than one specific set of environmental conditions, as a plant that can lead either a parasitic or a nonparasitic life or a bacterium that can live with or without air (opposed to obligate).

only common bullies, in some places (fry food seems to be the critical factor), and it becomes a selection pressure so the population quickly evolves to suit a non-diadromous lifecycle.

I guess Cran's and uplands would be described as obligate non-diadromous... but that classification is fairly redundant.

(alternatively, the short answer would have been "only common bullies can produce landlocked population, and only under the right conditions")

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Thank you for the lesson ;)

Common bullies from a non-diadromous population (eg a lake) should also be easy to raise in freshwater because they have evolved to not go to sea. In this case the eggs will be big (2.5mm length), rather than the usual diadromous common bully egg size (1mm)
I'm not positive where these common bullies came from but they could be from lake Arapuni so might be from a non-diadromous population. The eggs look larger than 1mm and I would say that they are close to the size of the Cran's bully's (why cant I think of a tidy way to shorten that to Cran's's ?) eggs.

Stella, will the fry be OK in a tank with just bullies or will I the other species (or even the same) eat them?

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definitely: :spop:

You could let the father take care of them until they are nearly ready to hatch (the eyes get really obvious) then transfer them to a fry tank. I think the eyes are first visible at nearly two weeks, then hatch a week later (temp dependent).

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The Cran's male is back at it with a different female. He is displaying and is black as black.

I cant get photos of the spawning this time as he has blocked up the entrance to the cave/nest that is right at the front of the tank

Edit:

Displaying in full colour:

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Well had a look under his rock today and there is definitely two spawns there and most of them look fertilised.

The first spawn are starting to show eyes. 13 days @ ~16 deg :bounce:

He has gone mostly back to his normal colouring, as in my profile pic, so I guess there are no more Cran's females ready.

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Another update 4/11/11:

Removed his rock to a 2ft tank, looks like maybe 15-20% of the first spawn has hatched (or been eaten) already in the main tank. The rest all have eyes and are turning in their egg-sack.

Mr bully now looks very forlorn with a new rock over his cave and he is chasing and flaring at everything, poor boy.

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Another update 5/11/11:

The first of the fry have hatched in the small tank, still attached to where the egg was but their tails, eyes etc are visible along with the yolk-sac

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Will try and get some better pics...

[Edit 01] Macro:

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[Edit 02] Some more macro shots:

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