Harlequin Spawning?

[MeanHoney]

This morning I did a 10% water change, adding RO water in an effort to lower my pH a bit. Right afterwards my two of my harlequins starting swimming around upside down rubbing their stomachs on the bottom of leaves. Are they spawning? I'd be surprised because my water is fairly alkaline (7.9) and moderately hard.

 

[paulf]

Doubt they are spawning... this is an extract from another site I wrote on breeding them

Breeding: Harlequins are one of the more difficult aquarium fish to breed, but if you have the right conditions they will spawn. When selecting fish to breed, females should be 10-20 months old, older than this and the females will often not spawn and two males should be kept for each female.

The depth of the water should be lowered to around 13-20cm, the ph around 5.3-5.7 and a GH of less than 3, the temperature should be 24.5-26.5 degrees celcius.
Once the tank has been set up and is running, the fish should be introduced to the tank in the late ofthe day as spawning occurs in the early morning and is caused by the rising of the sun. The spawning process takes anything from 2-3 hours and as many as 100-250 eggs can be deposited on the underside of broad leaved plants and the fry should be free swimming within 24 hours.

 

[Lateral Line]

What you describe is typical spwaning behaviour for the species. Eggs are laid individually on the under side of leaves and fertilised by the male who wraps himself around the female in the process. I've bred Harlequins several times. It is pretty unmistakable.

Many species will spawn in clean water, I've seen Neons scattering eggs in water over pH 8 and hard enough to blunt a knife. The eggs though, tend not to hatch. The Calcium ions in the water react with the egg shells making them to tough for the fry to emerge.

Adding RO water will have little effect on your pH, it will lower your hardness which will effect the buffering capability of the tank. You will need to reduce your hardness considerably before you can see an impact on pH. Be careful, water with low buffering potential can become very unstable and swing wildly in pH.

 

[MeanHoney]

That behavior went on for a couple hours and it does seem like they were spawning, since there are clusters of what appear to be eggs on the leaves of some of the plants. But given my water, it sounds like nothing will come of it.

Adding RO water will have little effect on your pH, it will lower your hardness which will effect the buffering capability of the tank. You will need to reduce your hardness considerably before you can see an impact on pH. Be careful, water with low buffering potential can become very unstable and swing wildly in pH.

For some reason the water that comes out of my RO unit is 6.9 PH and 6 d KH which seems like ideal water for harlequins. I thought by changing 10% of the water a couple times per week, I could gradually (and hopefully safely) lower both the KH and PH of my tank. Or won't that work?

 

[kuhliloacher]

I use Proper PH 7.0 by Aquarium Pharmaceuticals for both of my community tanks. It is available in 6.5, 7.0, 7.5 and 8.2. It works well. Instructions say not to change the PH more than .5 in 24 hours.

 

[Lateral Line]

For some reason the water that comes out of my RO unit is 6.9 PH and 6 d KH which seems like ideal water for harlequins. I thought by changing 10% of the water a couple times per week, I could gradually (and hopefully safely) lower both the KH and PH of my tank. Or won't that work?

Yes, it will work eventually. Your existing water will continue to keep your pH up for a long while though. If you are sure your RO is producing pH 6.9 and 6 KH, then you can continue. My RO water has almost zero dissolved salts, so is quite unsuitable for regular tank use hance my warning.

I use Proper PH 7.0 by Aquarium Pharmaceuticals for both of my community tanks.

Aquarium pH buffers are normally a blend of Acid and Alkali Phosphates. In hard water, you will need to use a lot in order to move the pH appreciably. Also phosphates are nutrients for plants and algae. There is always an algae bloom risk with using them.

A better stabilising salt is something like Kent RO Rite.

I'll add my normal disclaimer here, adjusting your water chemistry without really understanding what you are doing is dangerous.

 

[MeanHoney]

Thanks both of you for the advice. I'll probably keep up with the RO water changes, seems a bit safer then chemicals.