Hillstream Loach species determination

[vortex260]

Dear all,
My name is Martin and I am new to this forum. So this is gonna be by first post. I got to to know to the hillstream loaches by reading the Amazonas Magazine from Germany with a very nice article written by Charles König. I am having 2 hill stream loaches at the moment where I am not sure about the exact species and I would like to know before I add more, so I can choose the right ones. Maybe you could help me by having a look at the following pictures (which are probably not the best). One has larger dots and they are less dense, the other one has smaller dots and more dense. Both have a blueish caudal fin which has some red color above and underneath the blue part. They might be Gastromyzon scitulus and ctenocephalus. But it's hard to determine for me. Also I couldn't find any species on the species index that had such a caudal coloration even though you find pictures on the internet. But there the species declaration is not trustworthy in my opinion. I thank you in advance.

Best wishes,
Martin

[ch.koenig]

Hi Martin
Seems my yesterday's post got lost.
Your specimen are G. scitulus within the variations of pattern and colouring.
Very nice species.
I'm still trying to breed them (f2 generation). May be you are the lucky one
Cheers Charles

[vortex260]

Hi Charles,

thank you for your kind reply and also for clarification. I would have to be very lucky, if I could breed them, cause they are the only specimens I own and they would have to be the male and female. I would like to fill up with animals of the same species, but I think it will be hard to find G. scitulus in the shops and if so, to be really sure about the correctness of species declaration.
Nevertheless I will give breeding a try. I am about to restructure my 3,2 ft fish tank with more stones today, also got a stronger filter additionally to my 12000 l/h (3170 gallons per hour). Maybe I will put the two in a separate tank and try to breed them there and leave the bigger tank free for another species of gastromyzon, so I dont mix them. I am just afraid that you can never be sure about homogeneity of species in a group that you buy in a shop.
If you say F2 generation does that mean you already got offspring being the F1?

Best wishes, and thank you again!

Martin

[ch.koenig]

Hi Martin
Philipp Dickmann has been successful in making G. ctenocephalus spawn, just once. That's not breeeing, just spawning by chance. In German: "Zufallszucht". Starting with f3 it's "breeding". Three generations completed. P. Dickmanns article doesn't give a clue how to and how theyy do.
A word on water movement: important is not a fast current, important is a lot of oxygen. Current has nothing to do with spawning. Current prevents spawning. In their habitat all hillies choose a place where they can cling together in spawning and where calm places with a lot of nourishment wait for eggs and fry. At least the feature for all Sewellia, Erromyzon sinensis and Pseudogastromyzon sp. in my experience.
A tip: small tank with V-glass construction.
Homogenity: doesn't exist in trade since the 90es. Some years ago I could trigger the separation of G. viriosus before export. Since corona we are back to mixture total.
You have to do the selection yourself. After some time it becomes easier. I do it in the importtank with flashlight (up to a thousend specimen).
For sexing we need pics when they cling to th glass, ventral view.
Cheers Charles

[vortex260]

Hi Charles,

First, thank you for your advices. I really appreciate them.
Of course you are right, that one cannot speak of breeding, if you just get offspring by chance without selection. But nevertheless this would already be a really nice success.
If I understand you correct, you would reduce the current for spawning purposes? I already was wondering how it would be done in nature as the eggs must be drifted away by the water flow. I will also recheck your article in the Amazonas Magazine. I will try to have some current in the tank as well as a distinct area without such a strong water flow. All given the fact that they both are really Male and female. Maybe you can help me again with the determination.

The first 6 pictures show the specimen with lesser dots. (Sry if I am exaggerating)



The other four pictures show the one with more and smaller dots.



Thank you in advance.

Best wishes,
Martin

[ch.koenig]

Hi Martin
Female (6) and male(4) for me.
Yes, aeration not flow.
Cheers Charles

[vortex260]

Hi Charles,

thank you for clarification. Can you let me know on which traits your decision is based. So I could learn for the future. So far, haven a look on pictures from seriouslyfish of male and female g. ctenocephalus I am not able to define the sexes of my two specimens.

I set up a separated tank for the two with moderate stream and additional air pump. I will increase the temperature in the next weeks und see wether it will lead to some mating behaviour.


Best wishes,
Martin

[ch.koenig]

Hi Martin
Two differences: males show a right angle of pectoral to mouth part (first ray). And body shape-outline from pectoral to ventral fins is broader in females than males (like a long V).
Cheers Charles