Goldfish in Discus set-up

Hi there Prof. Dirk
Hope you are well.
I read about a German Discus breeder who keeps Goldfish in his recirculating Discus system. They are not kept in the same tank but form part of the whole set-up. His reason for this is that he says their presence lowers the ph due to acidification they bring to the water?
Now what baffles me is that a) its obviously not very comfortable for the Goldfish, b) what about the health risk this poses, c) Goldfish are messy and though I presume this mess it what causes the lower ph, surely it increases the bio-load negatively? This breeder states that he prefers this to peat moss. What are your thoughts?

Thank you,
Regards
Marco

 

The one way I can see this influencing the acidity of this tank, excepting the goldfishes' waste, would be the deaths of the goldfish themselves. Goldfish won't last nearly as long in warm water as they do in the correct environment (ie: cooler waters). Besides that issue, you're correct in saying that the goldfish and their generally 'messy' nature would only put more strain on the system's bio load. I'm only sure this could negatively affect the discus.

 

Hi Marco and Tim,

No I do not think that this is wise, for the following reasons:

1. Goldfish are cold water fishes and discus temps are too high for them so this will shorten their lives and I think this is cruel.

2. If your carbonate hardness is too high you will battle to reduce your pH. However for keeping and breeding discus you need low carbonate hardness so to think that you would reduce it in this way is wrong, you should start off with low carbonate hardness water and you will simply not have this problem of too high pH, you will rather be trying to keep the pH up as I find in my recirculating system.

3. The discus and the goldfish will produce ammonia which will breakdown into nitrate in the biological filter. You would have to change water to reduce nitrate levels again, so if you change the water again with higher carbonate hardness water, your pH will go up again, back to square one.

4. Then you simply want to keep the number of fishes in a discus system as low as possible, so adding goldfish just simply makes no sense whatsoever.

I would definitely not even consider this, sounds like some or other know-it-all again.

Kind regards,

Dirk

 

Thanks for the feedback Prof. Dirk. Its exactly what I thought. I just also thought there might be some 'mystical' reason I'm not aware of. I thought it would be counter-productive as the 'mess' that would ultimately 'lower' the ph will be detrimental to Discus, thus leading to more water changes and again a possible increase in ph and Kh. Thanks for confirming Prof. Dirk. Rgds, Marco

 

If it's not found in the wild that way, it shouldn't be in your tank that way. It's the equivalent of a human living at 46*C 24/7 . . .crazy