Angelfish Fry Gill Disease

Good day Prof

I noticed today that some of my angel fry are missing gill covers on both sides.

I use a mixture of ro and normal bore hole water (PH 7.5)
All my tanks are bare bottom with sponge filters, I do a daily water change of 50% on all my fry tanks (all tanks 100l) and +- 50 fry per tank
I feed them only BBS purchased from you.

Can you please help me with this problem

 

Hi Gerrit,

Let me first of all say that this is not a disease, it is not caused by some or other bug and it is not contagious.

This can be inherited, so the parents can carry the problem. If this was the case then you might find that one angel pair often has babies that have these problems but the babies of other pairs is without these problems. However, this is actually unlikely, it is rather the second problem that I will refer to after this.

I think that the most likely reason why this is happening is because of water conditions. You say you use RO water mixed with your borehole water. Do you know how soft or hard your water is after you make this mix? The simplest measurement would be to measure electrical conductivity, but it would help a lot if you could tell us what this is. However, the reason why this happens is because when the fish are tiny fry, I mean in the period between hatching and say 10 days afterwards, you did a water change with water that was softer or harder or had a higher or a lower pH. This then causes problems in the development of the gill covers. This is also a common problem in discus, and if you would look at the thread that Jason started after his discus spawned, I advised against water changes when the fry were so tiny for exactly the same reason.

So please check how soft your water is and let us know.

As a general word of advice, I also want to say to you that I would never do 50% water changes on angel fry tanks, I think this is total overkill. I assume you have good filters in those tanks, right? One does water changes to reduce nitrate levels, but the nitrate production when angel fry are being fed well is never so high, so I would cut back on this. I do 10% max per day on my fry tanks. I basically syphon off the mess and then top up with fresh water. It would save you a hell of a lot of money on electricity in winter if you did not do such large water changes.

Kind regards,

Dirk

 

Thank you prof for the great advice it make sense now, a few months back when these fry were very young i had a lot of deaths because of too hard water so i soften the water with the ro water, that sorted out the deaths but with these consequences. I will take a sample of my water to my local pet shop for an accurate test. I will post results tomorrow.

 

Good day Prof

I did a water test with a TETRA AQUARIUM WATER /TROPICAL TEST KIT, to follow is the results.

Borehole water: PH8.0, NO3 25, KH20, GH16
RO Water: PH6.4, NO3 10, KH3, GH8
Water Mixture for water changes: PH7, NO3 5, KH6, GH16

This is all i could test with the equipment available in Brits. Hope this will help.

 

I just have one comment/question. Is your mixture a mixture of the Borehole water and RO water? If it is then how is your NO3 lower in the mixture than it is in the RO water? It should be the lowest in the pure RO water. Just an observation.

 

Yes Brenton,

You are quite right in making your comment. I would expect that RO water would have a low pH and no measurable levels of NO3, kH and gH. If this is not the case it indicates that there is something wrong with the RO apparatus, it sounds like there may be a leak somewhere in your seals and that normal tap water is leaking past some of the membranes. When last did you replace the membranes in this apparatus and do you have a good prefilter to filter out floaties?

Gerrit, in general what I would do if I had this type of tap water is I would mix about 1 part of tapwater, perhaps even less, and 3 parts of RO water, but then it must be pure RO water and give zero readings as explained above. I would use a conductivity meter to prepare this water so that is absolutely constant, let us say at somewhere around 100 microSiemens per cm, and then if this is prepared with the same reading every time then you should not have this problem. A conductivity meter is also nice because you not need to use kits for measurements, just stick the electrode in the water and measure, very easy!

Kind regards,

Dirk

 

Thank you prof and brenton for the comments. I will replace my ro filters and membranes asap (it is about 8 months since i replaced the filters). I will start looking for a conductivity meter.

Thanks.

 

Good day Prof,

Just want to thank you for all the advice and want to say things are going really well with my angels but i must till get my water perfect for each water change. I have just one question, i am looking to buy a conductivity meter and was wondering if you can give me some advice on brand, model or supplier of a good quality conductivity meter. Been searching the web but i am afraid of buying the wrong thing.

Kind Regards
Gerrit