Sexing Smallmouth bass

Any of you fish geeks (I say that very respectfully as I'm impressed by the esoteric knowledge here) have any experience sexing fish by the appearance of their urogenital orifices, especially smallmouth bass, or know of some links or experts I can confide in?

I'm in my first year of attempting to produce my own smalmouth bass. I've moving fish from one of my main outdoor ponds to a smaller pond that is set up with beds made up of large boulders, gravel, landscape size stone and cobble size stones. I've moved 11 fish to this small 1/10th acre pond and fertilized it twice now.

My thinking is the larger more rotund fish of the species are the females as I seem to have two distinct sizes of fish although at this point in time even those fish do not look especially gravid with ovaries. I've even tried ultrasound and x-rays with less than stellar results. If anyone is interested I'd be happy to post pics of them.

I'm on a bent to see if I can sex them externally by comparing urogenital orifices and see if I can discern a pattern associated with the larger fish. Its seems I may have, but have only examined four fish as of yet.

Anyway, I sedated them and took the following pictures of the urogenital orifices. Anyone think they can see a notable difference in one or all of them?

The first and third fish were the largest and/or plumpest. It appears the urogenital opening is notably different of the first and the third fish vs. the other two? And the other two fish that were smaller seem to have very similar morphology? Or perhaps I'm just hoping it could be this easy? Thoughts?

I suppose I could sacrifice a few and cut them open to see if their a pattern in the appearance of the orifices but I really hate to as these are costly fish.

Here are the actual fish that correspond in the same order as the above pictures:

Males look to have a flatter and whiter belly. When no food in gut, stomach of males also tighter / harder. Males of all black basses I have observed tending nest site / brood seem to have larger pelvic fins. In northern largemouth bass and spotted bass the pelvic fins also seem to flouresce when male extends them, so color is generally whiter.

First looks to be female as urigenital opening appears to be taking on the _*-shape. It is also close to being ready to spawn.

Will you be feed training fry?

Males look to have a flatter and whiter belly. When no food in gut, stomach of males also tighter / harder. Males of all black basses I have observed tending nest site / brood seem to have larger pelvic fins. In northern largemouth bass and spotted bass the pelvic fins also seem to flouresce when male extends them, so color is generally whiter.

First looks to be female as urigenital opening appears to be taking on the _*-shape. It is also close to being ready to spawn.

Will you be feed training fry?

Hey long time no hear. Where ya been?

Yes I will be feed training the fry either in a cage or a flow trough circular tank. Probably the latter.

One problem I'm having is I've got some Chara that is out competing the phytoplankton. Cutrine Plus granular has no effect on it in my hard water. I'm going to try some raking before it's too late.

Do grass carp eat Chara? Tilapia?

az9,
In same place just keeping low. I post but seem to seldom get responses. If option presents itself, transfer some fry to RAS when only they are only an inch long, hopefully well before plankton crashes. Feed train them directly onto a crumb. For me, feed training best when bass have a very high exchange rate and stocked dense enough that that they are prone to jump out when startled.



Skipjack,
I do not rely on grass carp to control Chara sp. It seems not to be tasty so other plants targeted first. Grass carp can also be a major predator in a production pond and smallmouth bass fry are idiots at night making for easy pickings by slow going grass carp.

Do grass carp eat Chara? Tilapia?

Grass carp do but it's not a quick fix.

Edited by az9, 21 April 2012 - 05:37 PM.

az9,
In same place just keeping low. I post but seem to seldom get responses. If option presents itself, transfer some fry to RAS when only they are only an inch long, hopefully well before plankton crashes. Feed train them directly onto a crumb. For me, feed training best when bass have a very high exchange rate and stocked dense enough that that they are prone to jump out when startled.

Actually the concern is not plankton crashing but getting it going. By the time I would possibly have plankton overabundance issues and subsequent crash, they will probably have been moved to an RAS, flow through tank, or floating cage in another pond.

Actually the concern is not plankton crashing but getting it going. By the time I would possibly have plankton overabundance issues and subsequent crash, they will probably have been moved to an RAS, flow through tank, or floating cage in another pond.

With soil in your area, a strong zooplankton bloom should not be a nutrient limited development. If you pond has already cleared, then you may already have a bumper water flea bloom. Swim it to verify. Larval smallmouth can pound down even the largest water fleas as a first food.

Interesting. I'd still feel better if I got a little phytoplankton bloom going.

If zooplankton bloom very strong, then they may be grazing phytoplankton down. This is typical of ponds / lakes where predator pressure on larger zooplankton is light. Can also be a problem in a newly filled pond where zooplankton "seed" bank produces a strong hatch before phytoplankton bloom takes off. Additional fertilizer will aid phytoplankton in outstripping predation by zooplankton. Pond will also green up as smallmouth wittle down the zooplankton.

If zooplankton bloom very strong, then they may be grazing phytoplankton down. This is typical of ponds / lakes where predator pressure on larger zooplankton is light. Can also be a problem in a newly filled pond where zooplankton "seed" bank produces a strong hatch before phytoplankton bloom takes off. Additional fertilizer will aid phytoplankton in outstripping predation by zooplankton. Pond will also green up as smallmouth wittle down the zooplankton.

If you say so. However I've seen where filamentous algae got hold in a new hatchery pond and it was really tough to get a phytoplankton bloom going due to the competition. Since Chara is also an algae... The Chara is at least two feet think in one area.

The ponds are initially filled with well water. Once the iron settles out they are gin clear.

If you say so. However I've seen where filamentous algae got hold in a new hatchery pond and it was really tough to get a phytoplankton bloom going due to the competition. Since Chara is also an algae... The Chara is at least two feet think in one area.

The ponds are initially filled with well water. Once the iron settles out they are gin clear.

We fill our ponds with gin clear well water as well. With repeat use ponds, plankton bloom is rapid. Virgin ponds have a slower and more eratic bloom. Chara would have to cover a good portion of pond bottom to sequester enough nutrients to suppress bloom. How long has your pond been filled. My ponds generally go through a solid plankton bloom before filamentous algae can suppress / bring it down it unless pond was not thoroughly dried prior to filling.

We fill our ponds with gin clear well water as well. With repeat use ponds, plankton bloom is rapid. Virgin ponds have a slower and more eratic bloom. Chara would have to cover a good portion of pond bottom to sequester enough nutrients to suppress bloom. How long has your pond been filled. My ponds generally go through a solid plankton bloom before filamentous algae can suppress / bring it down it unless pond was not thoroughly dried prior to filling.

I normally leave them dry all winter for the most part but this one I drained last fall after fish harvest, limed it and refilled it about a week later. The problem with leaving my ponds dry for an extended period of time is I get erosion problems from the steep banks. I had the builder make the banks far to steep.

The Chara is over almost the entire bottom now.

We fill our ponds with gin clear well water as well. With repeat use ponds, plankton bloom is rapid. Virgin ponds have a slower and more eratic bloom. Chara would have to cover a good portion of pond bottom to sequester enough nutrients to suppress bloom. How long has your pond been filled. My ponds generally go through a solid plankton bloom before filamentous algae can suppress / bring it down it unless pond was not thoroughly dried prior to filling.

I have fry now and they seem to be doing O.K. However the water is getting clearer with the sudden drop in temps and the ever increasing Chara. I did have a decent algae bloom for a while.

I'm sending you a P.M. question on bluegills in an RAS. I'm hoping you'll respond if I give you a heads up here. Thanks!


Oh here are some fry in the water. Pitch black in color at first swim up!