Pel. sub. 'matadi' fry

[tjudy]

I have two pairs of 'matadi' that are both spawning for me on a regular basis. The spawns are very small though. I like to leave pairs with their spawns for the first couple clutches. When mom comes out with the broods for the first time (that I see them :wink: ) anyway), there have been less than a dozen fry. One pair is on their third clutch!!!!

I have been making the water softer and softer over the past month, and dropping the pH. Current conditions are about 75ppm TDS and pH 6.3. I do not know how I can get much softer short of straight r/o... our tap water runs 800-1000 ppm TDS, pH 8.3. I am wondering if the issue is fertilization rate, larval development or fry mortality.... :?:

Maybe I should keep more Tropheus... they're dwarfs too... :?

 

[Randall]

Small Hatch Rates

Dear Ted,

How large are your females? If they're two inches or less, then a brood of about a dozen doesn't sound so far off the mark. If you think it's a carbonate hardness issue, try conditioning your water with peat before performing your water changes. Have you considered diet at all? What are your fish eating?

Good luck!

Randall Kohn

 

[Richgrenfell]

Yeah, I say look at the diet. I get my female fish ready with a high protien diet. Chopped fresh shrimp, and bloodworms, along with daphnia and other things. What have you been feeding Ted?

Rich

 

[tjudy]

Mostly a combination of frozen, flake, and sinking pellet foods. They get live bbs daily, and live rinsed blackworms twice a week.. or so. One female is about 1 3/4" andthe other is easily 2 inches. They are laying more eggs than what is coming out of the cave. I have been able to see the plaques on a couple broods.

This current batch is small, but surviving. They have made it longer than any brood so far.

 

[Richgrenfell]

Sure sounds like enough protien. Well, they're young yet, give em' a little time.

Rich

 

[Randall]

Spawning Pelv. sub. "Matadi"

Dear Ted,

Thanks for the additional info.

Well, at 2" and less, it sounds like your females are quite young, but certainly, as they have demonstrated, of breeding age. Their age and size could, in part, account for the small number of fry. Although, like I said, a dozen viable fry from a 2" or less female doesn't sound so bad.

As far as diet goes, I'd lose the frozen foods and substitute with freeze dried plankton, blood worms, glass worms, daphnia, tubiflex worms and/or brine shrimp. Unlike freezing in water, the freeze dry process preserves many more nutrients. In fact, at the ACA Convention in New Jersey (2000), Rosario LaCorte advised not feeding fish frozen foods due to its low nutritional content.

Another possible explanation for the lower hatch rates may be related to carbonate hardness. With some soft water species, CaCO3 can prevent egg fertility and/or prevent fertilized eggs from developing successfully. It might be a good idea to test the KH, if you haven't done so already. If it comes up high, conditioning your water with peat should help.

My final suggestion is to test the conductivity of your aquarium water. You reported the TDS earlier, but I don't know the TDS to conductivity in microsiemans conversion factor. If your conductivity is coming in at over 300 microseimans/liter, that, too, could account for the lower hatch rates.

Good luck!

Randall Kohn

 

[tjudy]

Conductivity is 150. The conversion factor is .5 tds:1 ec. I have not tested it, but I am positive the carbonates are high. I use Acid Buffer to reduce the pH. That product is advertised to convert carbonates into CO2.

Thanks all...