I have a pair of C. alvarezi that I purchased as juveniles this past spring. I recently set them up in a breeding tank & pulled about 15 eggs, all of which hatched. However, after the first two weeks, all but 4 had died. I'd fed them baby brine, along with paramecium just in case, but they were obviously large enough to eat the brine shrimp.

They were all eating for the first few days, but the 4 started growing while the rest did not, and eventually died. These 4 are nearly 4 weeks old now and are still doing well and growing.

I actually had a similar problem last year when I bred C. fontinalis, losing about 75% of each hatch after the first 2 weeks. However, I just spawned them enough times to get enough juveniles for my BAP points, so I never actually solved the problem.

Does anyone have any insight on what could be causing this problem? Thanks.

I had nothing but trouble breeding C.fontinalis. Seems they were susceptible to disease and stress. I eventually started hatching them in the water the parents lived in, to avoid water chemistry issues/fluctuations that could be attributing to the mortality. I also began treating the new adults to the room with formalin/malachite and a treatment of Flubendozole... This seemed to help.

Good luck...

Markus

Over 15 years of working with pupfish and hatching a few thousand eggs usually getting eggs is the hard part, however, I am trying to see where in my method I can help. Early in the game I had obtained water chemistry data for typical habitats for these fish. The biggest mistake most make is believing you add salt to the water to maintain pups - WRONG. These fish come from waters supplied by groundwater where the subsurface can still have "salts" dissolved into the groundwater. The salts you are dissolving are primarily calcium and magnesium carbonates (sodium chloride is low), your water is hard. Public water supplies try to limit hardness but if your water is on the hard side it will also be more alkaline which also will be bad for the fish. My recommendation is to develop a standard for your water, even making it up to a hardness and continue to make your water to this formulation. Also, adapt all of your breeders to this water chemistry.

I have soft water, really soft, 50-100 ppm out of the tap. I make slightly hard water, about 250 ppm. My mix for 18 gallons of water (volume of a Rubbermaid 18 gallon storage tub) consists of the following: 16.3 grams of Instant Ocean, 9.6 grams of magnesium chloride (I use a product called MAG, a hydroscopic flake used as an environmentally friendly non-sodium deicing agent)(do not use epsom salts, do not add sulfate to your water), 6.5 grams of calcium chloride (Prestone driveway heat is basically 98.5% calcium chloride), and 1.6 grams of potassium chloride (salt substitute from the grocery store works here in small quantities) and then 22 grams of sodium bicarbonate (Arm & Hammer baking sodna) but do not mix this with the other salts because water the MAG picks up will dissolve bicarb and basically generate calcium carbonate which will not dissolve readily.

It is having this consistency of water so when you add water to fry or change water you don't shock the fry. Without this consistency you have the potential of having osmotic shock on the developing gills of the fry.

Second, consider temperature - since I was usually breeding the pups at ambient temperature this meant no heaters in the tank so your eggs were incubating at ambient temperature and then growing in rearing containers at ambient temperature - hence during the normal breeding season I would breed the pups from June 'til September in my "greenhouse". In the past I noticed that fry hatched and reared indoors at a constant temperature tended to have lower survivability. For some reason I believe the fluctuation in diurnal temperatures for the first 2-3 months of the young fish life tended to "toughen" them and make them healthier.

This is probably one reason that most people who atempt to work with pups eventually settle on the "natural" method and succeed by basic recruitment.

If you don't needs thousands of gallons of hard water, I would suggest this product from Seachem. Is is a little heavy with sodium, but the tanganican formula is a fairly good balance in my opiniun. My tap is 20-40tds and I add enough to bring it up to 240tds with this product.

http://www.seachem.com/Products/produ ... ges/TanganyikaBuffer.html

Keep in mind though, Dave knows his pupfish! I've dabbled for a few years with success with this method and product use. A 1.1lb jar makes hundreds of gallons of water for me and my water needs..Not to mention, it works great for some of my live bearers and L. Tanganicanus.....

Markus

Here in Missouri, we have extremely hard, alkaline water. It sometimes goes down after heavy rain, but our pH is typically between 8.0 and 8.6 (sometime up to 9.0), and very high carbonates.

I probably should have described my setup first: I have the pair in a 5-gal tank, with a crushed-coral substrate, about 1 Tbs sea-salt per gal, and temp at 80-84 F, with a standard floating spawning mop. Are you saying I should omit the sea-salt?

Like I said, I'll often pull 5 or 6 eggs per day, most of which will hatch. I just put them in a small tub of tank water, floating in the parents tank to stay warm. However, I then start losing fry almost immediately, even though they appear to be eating.

Yeah, I don't think the salt is doing you any good. Is your source for water public or a private well? Missouri River water?

BTW, I use bottom mops - try adding more than one. Don't know how aggressive your males are but females tend to take cover in the mops and then graze on their own eggs. You are probably finding your eggs deep in the mops, especially near the "knot"?