Are all my CPDs male?

[rockpaper]

I got a set of 10 celestial pearl danios about a week ago. They were thin and pale when I first got them, so I couldn't figure out their sexes. Now that they've brightened up a bit, I'm... concerned.

Please tell me that I didn't get 100% male celestial pearl danios!

Also let me apologize ahead of time for the awful pictures... these are literally the best ones from a 10 min photoshoot

Some (very bad) pics of the ones I think look most "femme":

Please help... My guppy has seemed a little stressed since I added the danios and my anxiety humor says "he's scared of all the macho-guy CPDs"!

 

[chickennublet]

There are a few differences between males and females for this fish. I think the most obvious one is in the colouration of the abdomen. In females, the front of the abdomen is white or cream coloured. In males the white-spotted blue colouration covers the entire abdomen.

Females also have colourless pectoral and pelvic fins. The pelvic fins of males are red/orange with black stripes and the pectoral fins are striped (but because these fish are so small it might be difficult to see if their pectoral fins are coloured or not) In females, the dorsal, anal and tail fin have less colour than the males.

Reproductive females also have a black spot just before the anal fin. The males don't have that black spot.

The photographs are not very clear at all but I do think there is at least one female.

 

[rockpaper]

Thank you, these are perfect guidelines! I see several individuals with dark spots before their anal fins, and many of these have the coloration you described as well.

One interesting thing is that my brightest, most orange, and shiniest individual has the anal spot you described. Now I'm wondering whether I got lucky with a very colorful and bright female...

Bonus, my guppy got more active when I put in a tiny surface skimmer today. I had tested my dissolved oxygen and had enough, but now that the gaseous exchange is improved he seems a lot happier.

Lots of wins today. Thank you again for your help

 

[dw1305]

Hi all,

I had tested my dissolved oxygen

What did you test it with? <"Dissolved Oxygen meters work">, but are expensive bits of kit. The <"test kits they sell"> are just a mechanism for transferring your money to them.

cheers Darrel

 

[rockpaper]

Hi all,

What did you test it with? <"Dissolved Oxygen meters work">, but are expensive bits of kit. The <"test kits they sell"> are just a mechanism for transferring your money to them.

cheers Darrel

The test I use is a consumer-grade Winkler titration from the brand Monitor. It's a cheapo kit but I've done Winkler titration many times in lab settings. Here's an older review (2001) discussing field testing methods for DO measurement, with Winkler titrations coming out on top for precision, accuracy, and correlation with other methods. If anyone wants to read the paper and doesn't have institutional access, I might be able to drop a pdf into a private message...

I am delighted to see the discussion of the different methods, though! I will say that I agree with you wholeheartedly that Winkler might not be the best tool for all hobbyists. There are a lot of ways the titration can go wrong, many sources of error, if the steps are not strictly followed. For example, I had several weeks of data collection ruined on a field site because I didn't correctly prevent oxygenation of the sample during the collection process... basically, I was introducing oxygen to the samples as I collected them, and look! Plenty of oxygen! It was so fun going back to those places to get more samples.

Moreover, I don't know about the reagent quality for the consumer kit. In the lab setting, we create all our own reagents for the titration, so I feel confident in the concentrations of acids, sulfates, etc.... because I made them. The kit I got seems good, no precipitates in the bottles, the reactions proceed as expected... but the accuracy cited in the paper might not be true in consumer kits, I don't know.

We did have an ancient DO meter in our lab, but it was older than I am by a decade or more. We sometimes used it to develop reliability in the titrations, but mostly it was just a cool old thing around the lab

 

[dw1305]

Hi all,

The test I use is a consumer-grade Winkler titration from the brand Monitor. It's a cheapo kit but I've done Winkler titration many times in lab settings.

In the lab., following the <"correct protocol"> it works fairly well. In the field, or <"with non-experienced operators">, DO meters are a game changer. You calibrate them in the field and they have automatic temperature compensation etc. <"Not everyone"> is a fan, so I'll add in @DeadFish .

I am delighted to see the discussion of the different methods, though! I will say that I agree with you wholeheartedly that Winkler might not be the best tool for all hobbyists. There are a lot of ways the titration can go wrong, many sources of error, if the steps are not strictly followed. For example, I had several weeks of data collection ruined on a field site because I didn't correctly prevent oxygenation of the sample during the collection process...

That is the normal problem, a larger gas exchange surface area leads to an increased, and anomalous, dissolved oxygen reading.

Moreover, I don't know about the reagent quality for the consumer kit. In the lab setting, we create all our own reagents for the titration, so I feel confident in the concentrations of acids, sulfates, etc.... because I made them. The kit I got seems good, no precipitates in the bottles, the reactions proceed as expected... but the accuracy cited in the paper might not be true in consumer kits, I don't know

It should list the reagents on the bottle? <"Dissolved Oxygen by the Winkler Method">.

We did have an ancient DO meter in our lab, but it was older than I am by a decade or more. We sometimes used it to develop reliability in the titrations, but mostly it was just a cool old thing around the lab

There can be issues with the <"gas permeable membranes">.

If you want to do it properly then you need a <"biotic Index"> in the field, and <"5 day BOD test in the lab."> followed <"by a bioassay">. The problem is that you really need a <"dedicated lab">.

The most sensitive metric is the <"biotic index">, it really can't lie.

Cheers Darrel

 

[rockpaper]

The photographs are not very clear at all but I do think there is at least one female.

How about... 2/10 females?

Hoping someone can give advice, because after spending a lot of time thinking about this over the last week or so, I'm basically convinced that I have exactly two females and eight males. I can identify them by the fact that they are visibly fatter when looking down from above, they both have their distinct anal spots, and from their behavior.

The two females spend most of their time in hiding, and when it's time to feed, they come out to eat a bit and get relentlessly chased by the males for the next half an hour to an hour, minimum. They both seem stressed out, which really bothers me, because one of the females is the most beautiful CPD in the tank and I'd like to breed her. The other female is much smaller and honestly seems to be the most stressed out, unhealthy fish in the tank; I am sure she will be the first casualty if I start having deaths.

I'm working on adding more hiding spots, but I can only get more CPDs via mail (one LFS has a severe ich outbreak atm and the other one doesn't stock nor special order CPDs, ever), so balancing the ratio will be very hard. I am working on getting a breeding/fry tank set up, but it will be very small given the space constraints of my living situation (3-5 US gal), and it would be a few weeks minimum before the tank was stable enough that I could move the females into it even temporarily.

Suggestions/advice on how to help my female CPDS given the bad M:F ratio?

It should list the reagents on the bottle?

Thanks for the info Darrel-- I decided not to trust the titration and just to increase the flow and surface agitation anyway.

RE: the reagents, I only meant that they could have been mixed in incorrect concentrations, or with contamination, etc. In my lab, I don't even trust reagents made by my colleagues-- I make them all myself so I can be sure they were done correctly. I trust a random manufacturer even less!

 

[Disaronno]

I am working on getting a breeding/fry tank set up, but it will be very small given the space constraints of my living situation (3-5 US gal), and it would be a few weeks minimum before the tank was stable enough that I could move the females into it even temporarily.

As in cycling a tank from scratch? I'd transfer some cycled media, substrate and spare plants into the temporary tank and call it done. The females would likely be harassed to death during the multi-week cycling.

 

[rockpaper]

As in cycling a tank from scratch? I'd transfer some cycled media, substrate and spare plants into the temporary tank and call it done. The females would likely be harassed to death during the multi-week cycling.

Yikes, you think so? I was hoping the situation wasn't so dire...

I'm not trying to cycle the tank from scratch, but I'm running a sponge filter in the main tank that I hoped would acquire the necessary microbiota over the next few weeks to "instant cycle" the secondary tank. The main filter in the primary tank is a canister, and it's still so new itself (7.5 weeks as of today) I'd rather not remove media if possible. It has been very stable since I finished cycling it, however-- I test daily, and there's never been nitrite or ammonia since before I started stocking (with now 10 CPDs, 7 amanos, 12 neocaridinas, a nerite, and a guppy).

I was hoping to avoid plants in the secondary tank, since tending to their growth needs could add unnecessary complications to the spawning process (and I haven't even finished tuning the growth process on the first tank), but I do know that would be a way to speed up the nitrogenous waste processing capacity.

I wish I had the sponge filter I put in the tank on day 1, but my beloved spouse tossed it out when they (honestly very kindly) cleaned out the 5 L vase I was keeping my nerite in for a fenbendazole dose

 

[dw1305]

Hi all,

I decided not to trust the titration and just to increase the flow and surface agitation anyway.

It makes sense, you don't actually need to know the level of dissolved oxygen that you have, you just need to ensure <"you always have sufficient">.

In my lab, I don't even trust reagents made by my colleagues-- I make them all myself so I can be sure they were done correctly.

I think a few of my colleagues might put me in the <"don't trust"> category. Personally I really like <"serial dilution"> as a technique for mitigating for my <"lack of GLP">.

They both seem stressed out, which really bothers me, because one of the females is the most beautiful CPD in the tank and I'd like to breed her. The other female is much smaller and honestly seems to be the most stressed out, unhealthy fish in the tank; I am sure she will be the first casualty if I start having deaths.

Can you break up <"line of sight"> any more? You could use a plant like Hornwort (<"Ceratophyllum demersum">) or <"structural leaf litter"> etc.

As in cycling a tank from scratch? I'd transfer some cycled media, substrate and spare plants into the temporary tank and call it done. The females would likely be harassed to death during the multi-week cycling.

What @Disaronno says, and their plan of action.

I was hoping to avoid plants in the secondary tank, since tending to their growth needs could add unnecessary complications to the spawning process

Honestly, plants are always your friend. You just need to choose suitable plants that are <"difficult to kill"> and will grow on <"petrol (gasoline) fumes">. The way I look at is that plants are an <"integral part of the biological filtration process"> and <"all tanks"> are better with them.

cheers Darrel