why do all my fish die?


New member
I can't seem to keep any fish long term. I have a 4ft 120g tank with a 125g basement sump. Roughly 190 gallons of water volume and aproximately 140lbs of live rock. The list of fish I have lost over the last year is as follows: 12 blue/green chromis, 3 bangai cardianls, 3 anthias, 1 gold bar cardinal, blue damsel, yellow corris wrasse. The only fish I had left 6 weeks ago are a kole tang, yellow tang, blue mandarin. I had 9 chromis, 1 bangai cardinal, 1 blue damsel, 3 anthias. After looking over the tank and testing the water parameters and also having the local fish store double check my results I decided to add more fish to the tank again. I added 9 chromis, 3 gold bar cardinals and a hector goby. That was a week ago. I have currently lost 3 chromis ( one jumped into the overflow and died in a sock filter overnight) and a goldbar cardinal. I checked all the parameters again. Nothing is out of whack. I feed well, twice a day alternating between small pellets, flakes, nori, mysis, and krill. The fish seem to do well at first then will start becoming anti social, stop eating then die. I don't see any signs of disease or trama to the dead fish. Any ideas?

here are the test results and for whats its worth, I've been tracking these two weeks (1 week prior to adding fish)
sg 1.025 steady
ph 7.85-8.04 over the two weeks
mg 1300-1400 over the two weeks
ca 560-600
kh 7-7.95dkh (was dosing and raising to 8.5ish but had a coral stress out so stopped dosing for 3 days until kh dropped back to 7.5dkh
No3 0.0
Po4 0.05-0.13
temp 77.9-79.9 doesn't have any major swings, less than 1 degree change over a 24 hour period
ammonia 0.0


New member
I noticed the PH is lower that what it should be, but it came up. I always keep mine at 8.4 and my fish are really healthy and active. This may or may not be the case but you might want to check that out.


New member
Couple of things you could start doing is first off quarantine all your fish before you add them to the tank. This is something a good majority of hobbyists don't actually do, and could help to prevent a lot of headaches. Second is I personally wouldn't add 13 fish all at once if that is actually what your doing. Chromis also have a tendency to pick each other off, so I would stick with a smaller number than 9 in a 120.


New member
Flukes can not be seen
Do the fish have cloudy eyes? Do thy breath heavily? Do thy swim in the power head most of the time?

Reef Frog

New member
Have you ruled out

-Stray voltage
-Contaminants introduced by additives, media, food, salt, your hands etc

Did all the fish come from the same supplier? If so perhaps a clue. Hope you get it sorted out.


New member
So here are the answers to the comments:

0.00 stray volts measured from the ground of the outlet to the water. I use a ground probe to help eliminate the issue.

I didn't add all the fish in one day, they were added over two weeks.

Honestly I didn't quarantine these fish but do typically quarantine all my new fish.

The fish I've kept and lost have all been from different sources. A lot of the have come from local reefers tanks. The fish I've received from the local's, were doing well and had been in their tanks for months if not years. The last group have come from the pet store.

The fish don't seem to be swimming in strong currents or gasping. Typically they seem to be eating well, then just drop.

Ph has always been an issue for me and if my understanding is correct, then I would think that there is a low amount of oxygen in the water column. I know that my house has a large amount of Co2. I have a wife, 4 girls and two dogs. I've also been doing some extensive weatherization to help offset heating/cooling costs. I have already put the skimmer intake outside and also my put an air boot onto my furnace. These have both have made a difference. When the skimmer is shut off for any length of time, the PH drops to about 7.5 ish.

I've thought about using kalkwasser to help with PH issues but don't have a reactor. If anyone thinks it would help without making things worse, I guess I could give it a shot.

I remember posting in the reef chemistry forum here and I was told alkalinity was more important than the reading of PH and to focus on keeping that more stable.

I have about 900-1100gph flowing through sump and three power heads inside the tank that equal aprox. 2200gph. Two of them are close to the surface and keep it agitated. The same can be said for the sump, the skimmer output keeps the water in the sump agitated as well as the output from the GFO/Carbon reactor.

I appreciate all the responses and time


New member
My advice is to pull the current fish out of the tank and QT them, and let the DT go fallow for a while. Best guess would be the fish brought something in with them that could be killing your fish.


New member
Do you have a sand bed? How long have you had it, has it sat at all not in water?

Do you have inverts or corals in the tank and if so how are they doing?