Harlequin Rasbora False Spawn?

[misterdude89]

I have a 29 gallon well planted tank with 10 Harlequin Rasboras(2 males, 8 females) and Otocinclus. Every morning since I first put the fish in the tank, I see males and females exhibiting obvious spawning behavior on the underside of the leaves in my "ludwigia forest". However, I'm never able to find the eggs or see any hatched fry. Maybe this is because I'm not sure exactly size and appearance to be looking for. Is it possible they aren't actually laying the eggs for some reason? Ph is a stable 8, 300+KH and GH. No ammonia or nitrites. Nitrates stay around 10. I realize this is not the right parameters for spawning in this species, but they are obviously happy enough with it to continuously exhibit the spawning behaviors. I also realize you're supposed to separate the mating pair to a breeding tank to lay the eggs to avoid predation of the fry, but i've been watching the tank intently all day and don't see the rasboras hanging around the ludwigia much except to spawn in the mornings. Anybody have any experience with this situation and could provide some insight?

 

[Colin_T]

If your GH is around 300ppm then none of their eggs would hatch anyway. They need really soft water with a GH below 50ppm for the eggs to hatch. The pH also needs to come down to below 7.0 for the eggs.

There might be snails eating the eggs or the other fish are eating them.

They might not be able to get the eggs to stick to the plant leaves and the eggs are sinking to the bottom. This would be GH and KH related.

Try feeding the adults more often. Feed them 3-5 times a day and see if you get eggs. Make sure you do a few more water changes hen feeding more often so the tank stays clean.

 

[misterdude89]

Thanks for the advice. I have looked into lowering ph, kh, and gh. Already have driftwood, but it has no effect since KH is so high. Peat moss looks like a possibility. However, can't find a definitive guide on how to use it to lower ph at a safe, slow rate. Also there is the issue of keeping it stable since my tap water has high Ph,KH and GH. And i don't have snails, and I watch the other rasboras throughout the day and never see them in the ludwigia except when spawning so I'm fairly confident predation is not the issue.

 

[JuiceBox52]

Thanks for the advice. I have looked into lowering ph, kh, and gh. Already have driftwood, but it has no effect since KH is so high. Peat moss looks like a possibility. However, can't find a definitive guide on how to use it to lower ph at a safe, slow rate. Also there is the issue of keeping it stable since my tap water has high Ph,KH and GH. And i don't have snails, and I watch the other rasboras throughout the day and never see them in the ludwigia except when spawning so I'm fairly confident predation is not the issue.

Peat moss will barely make a difference. You will need to use RO water

 

[Colin_T]

The easiest way to reduce the pH, GH and KH is to dilute your tap water with rain water, distilled water or reverse osmosis (R/O) water. These types of water have no minerals in and when mixed with your tap water, they will reduce the overall mineral content and lower the pH, GH & KH.

 

[misterdude89]

Thanks for the tip. Any guide on mixing ratios? How much I should i be changing with tank water per instance and how often to start bringing ph down?

 

[Colin_T]

Start off using a 50/50 mix. Make up the new water in a container first and aerate it for 30 minutes. Then use that water to do water changes. When you make up the new water, add tap water first, dechlorinate it and aerate for 5-10 minutes, then add the R/O water and aerate for another 15-30 minutes.

Do 20% water changes every couple of days for a few weeks, then increase the water changes to 75% once a week.

Check the GH after a month and see what it is then.