My fish were very active and eating very well, since about 2 days ago
they are hiding and not eating well and some, not at all.
These are angelfish, neon corys, 11 otos, 12 cardinal tetras.
Six (6) cardinal tetras have died in the las 3 days and think they are the ones with very drawn(empty) stomachs.
125 gal/100 gal net started 9/17, planted tank 10/11.

The significant change that I notice is PH now 6.4 from 6.6.
Have been dosing the same for 6 weeks except for a small increase in Plantex
and new dosing of Epson salt , 3.0g, 2x week.
Temp is about 80-82 F and steady.
There is green algae. Today I changed 50% water and they came alive for a while in the fresh water but reverted to the above behavior.

Any ideas?

tks

Did you use Prime or an equivalent dechlorinator? It almost sounds like you have something like chlorine or ammonia in the water. Do you dose CO2, and how do you measure how much you have in the water?

Yes I used dechlorinator (fish's behavior improved after water change).
Ammonia is -0-
CO2 - 35PPM (KH 53.7 , PH 6.4)

I had PH at 6.6 for a while but increased CO2 (lowered PH) to fight algae.
I am going to increase PH to 6.6 as this seems to be the problem.

Any other ideas?

tks

Is this a typo? Should it read 5.37 or is this 53 ppm? It's very easy to gas the fish if you measure CO2 incorrectly. Are you calculating the CO2 based on the tank water parameters or are you using a drop checker with 4dkh water? If you are using the tank water you can be way off in either direction.

Cheers,

Have you tested nitrite? From what I've heard nitrite poisoning hits cardinals particularly hard. It will cause the fish to suffocate because it affects how they are able to process oxygen. How big is the tank? How long has it been set up? Anything you did right before this started happening?

I am measuring my CO2 with my aquarium water, my KH and PH readings.
I don't know what a drop check is. Could you point me where to find out about it and which one you use, etc?
My PH has been 6.4 (35ppm C02 per table) brought it down today to 6.6 since fish were ok at that PH level ( so now CO2 should be at 23ppm)
My KH ..53.7ppm (3 degrees K)
My Nitrate today 20ppm (I just dosed fertilizers including KNO3)
My fish were happy Oct. 27 for sure, changed 50% water and added, for the first time: 1/4 tsp MGSO4(EPSON SALT) and
30ml of Excel. Obviously I overdosed. Have stopped using excel until I understand it.
At this point some fish died off.

Today I have installed a 25 Watt UV sterilizer to help with diatoms and green algae. BBA has started to appear now.

Your opinions would be appreciated

I don't think the problem is CO2. When we measure CO2 by measuring the tank KH and pH that almost always gives too high a number, not too low. Here is an article on drop checkers:Drop Checkers/CO2 Indicators-Why and How. Here are some sources for them: Boyu Drop Checker Type 1 [5654] - £12.99 : Aqua Essentials,
Chame Co2 Drop Checker - Live Aquarium plant fish tank - (eBay item 250183686041 end time Nov-10-07 18:37:59 PST),
http://www.aquaticplantcentral.com/f...-checkers.html

I'd say Carissa was on the mark. I'd test for nitrite, and if that came back negative I'd probably test it again ! Nervous behavior and going off there feed, the very 1st. place to start is nitrite. Annoxia would produce lethargic behavior so Co2 is unlikely. By now the nitrite may have cycled through. Did you make any recent changes to the system or any large additions in livestock or feed ? Did you do any extensive maintenance recently ? During nitrite surges the water may appear to be unusually clear (Visually clean) while the livestock appears to be distressed due to the hemoglobin being bound with nitrite. Fishes vital chatoyance may appear to be dark, dull or grey to black. Neons/cardinals red shade will wash out white. Discus will shadow black. Corys will spaz out severely.

Excess copper will have similar indicators, but that's unlikely unless you have a known source in your makeup water. HTH. Prof M

It is a new tank.........

More water changes, good CO2/dosing, maybe add some Zeolite, carbon etc, purigen etc

These fish really are not acclimated nor is the tank.


Regards,
Tom Barr

Could the fish problems be because of the Excel? Didn't you say that is when you began to see problems? I have read that overdoses of Excel can sometimes affect some of the more sensitive fish/inverts.

But...you said you dosed 30ml. of excel in a 125gal. tank....I have used doses of half that - 12-15ml. - in my 29gal. tank with no effect on my shrimp.....so 30ml in a 125 gal. tank might not really be that much.

Just something to consider as well.

-Mike B-