22 replies to this topic

[csm]

As a hobby, I've had a outside pond (about 1200gals) for about 18months. It contains both koi and goldfish with some vegetation to augment the filter. Everything was running fine till three weeks ago. The koi (8-12") started to die at a rate of 1-2 overnight. I've not done anything to change the environment in the last month. I've checked all the basics - PH, nitrates, ammonia, nitrite - and everything is in acceptable range. Also saw no visble clues on the dead fish - blackening, white spots, ulcers, etc.. I changed out the at least 30% of the water three times since this started. Last night my largest one - 24" - died. I've talked, many times, to the store where I get my fish and they can't seem to diagnose either. I've upset and fustrated at what's happening. Anyone have any ideas?

[nc0gnet0]

How are you testing your water (with what kit)? What are your levels? Did you add any new fish to the pond before this started happening?

[nc0gnet0]

Are all the fish dying at night? Do they show any signs of stress during the day or are you saying that they look fine right up until dusk and when you awake the next morning you have dead fish? if this is the case it may suggest oxygen depletion. But if you are seeing sick fish during the day it may be this or a disease or a combination of both.........

[csm]

I'm using API (Aquarium Pharmaceticals) Freshwater Master Kit. The PH level 7.2, Ammonia is 0.2ppm, intrite is 0.1ppm, nitrate is 0ppm. I did add four new koi about a month ago. I normally add about 3-4 fish (includes shibumbkin and comets) every couple of months.

[koiguy1969]

are you quarentining you fish before tossing them in the pond?

[csm]

I also thought O2 depletion is one of my leading contenders. However, the fish seem to be feeding well, showing a lot of energy and not gasping for air at the surface during twilight or dawn. I do plan to buy an emergency aeration unit to eliminate this possibility. Please keep the suggestions coming as I want to rule out as many possibilities. It is sad to see such lovely creatures systematically die.

[csm]

i quaratine them in a separate 10 gallon tank prior to introduction

[nc0gnet0]

How many fish do you currently have in the pond and their approximate sizes? Do they apear healthy during the day or are they showing signs of stress then too? You may have sick/stressed fish that aren't dealing well with the changing parameters at night causing your night time die-offs. First thing I would do is add some airstones to the pond or a spray bar. This isn't a cure, its a stop gap to buy you more time to treat the sick fish. Your ammonia levels are a bit high, possibly an overstocked pond. I also highly suggest taking the same readings at night (say 2:00 am) and see if you have any large fluctuations.

Once again these are not cures but steps you should take to insure a stable environment to treat your sick fish.

Is your water clear or do you have a significant algea bllom in progess (ie: green water).

[nc0gnet0]

air can never hurt, thats for sure. Have you rulled out the possiblitliy of large PH fluctuations at night? I am askign these questions as because it appears that the fish show no signs or symptons during the day and then suddenly die off at night.

[csm]

excellent questions and suggestions. i haven't taken PH readings at night. the water is clear. I've just completed draining/repleshing 50% of the water. i'm off to get a spraybar/airstones.

[nc0gnet0]

If you have an extra pump making a spray bar is really easy and inexpensive. All you need is some 3/4 to 1" pvc pipe, and end cap, a drill and a fitting that will attach to one end of your pvc pipe and then to your pump hose. Put the endcap on one end and cement it in place. Drill holes down the bottom of the pvc pipe, then place the fitting on the other end and connect to your pump. Position the spray bar so it sprays down into the water and place it about 6" above the surface.

[nc0gnet0]

Is the Ph and temperature of the water you are replacing the same? Be carefull such large water changes all at once can shock the fish as well if the parameters vary. Are you dechlorinating? personally I would most likely do a series of 10% water changes rather than a 50% one all at once.

[KOiPond]

Yikes I'm so sorry this is happening to you, good luck!

[csm]

This is a great forum! Thank you all for your suggestions. I've just placed the air stones.

I realize that 50% water change is drastic. Having tried the graduated changes prior, I guess I somewhat panicked. All measures are moving to the ideal zone. Although, the ammonia level has crept up a little to 0.2 and I'm monitoring.

I have been getting conflicting advice from the store that sold the fish over the last three weeks. (By way of context they focus mostly on acquarium products). It confirmed today they mayhave hit their knowledge limit in this area. One thing that they are insisting on 'starting afresh' - transfer the fish into a temporary area; remove all the leaf debris at the bottom add a 'skimmer' for greater filtration and aeration. As a novice, this seems way too radical. Any advice?

I'll keep my fingers crossed tonight when I take another set of measures!:

[newday3000]

csm said:

Ammonia is 0.2ppm, intrite is 0.1ppm, nitrate is 0ppm. I did add four new koi about a month ago. I normally add about 3-4 fish (includes shibumbkin and comets) every couple of months.

Ammonia should be zero and so should Nitrite. Adding 3-4 fish (what size?) probably overloaded your bio filter over a month and built up ammonia which is likely what is causing your fish to die (with ammonia poisoning . How many 8-12" Koi do you have? This size fish produces a lot of waste and adding 3-4 all at once will spike Ammonia.

If you are still measuring any ammonia at all this is your problem. Water changes to reduce ammonia and you may need more bio filter to keep up with the bio load since you've been adding fish to a 1200 G pond.

PH reading matters at night since the effects of ammonia at higher PH is more lethal than at lower PH reading. Ponds naturally increase PH at night due to plants releasing CO2 which increases PH and turns the .2 ppm ammonia into lethal levels at night. This explains why they die at night. Look at the back of your test kit most show ppm versus PH to show when it becomes lethal to fish.