Backyard Aquaponics
A place to discuss aquaponics

I am beginning to think I am not cut out for this.

So a few weeks ago, i noticed some of my plants were being nibbled at, so I put some mouse traps in and caught a mouse. Kept the traps there, and while a few nibbles still occurred, after a few traps got sprung, it seemed ok. That is until last week. Garden absolutely devastated. Leaves stripped, chilies eaten, dill, parsley, cilantro, kale, amaranth, lettuce, decimated.
So i setup a camera and found the culprit to be at least one rat. (identified last night). Today i have purchased larger traps and better rat attractant for them.
However when i got home today, i found 11 of my SP dead. just over half of my fish population dead in a day.
Tested my water (do it weekly and all was ok last week) and Nitrates are up to 80ppm, ammonia 0.5ppm. PH is unwavering at 6.5 nitrites are nil, salinity is at 3.4ppt.

Water temp is relatively stable, ranging from 22 - 24C

I am theorising that the nitrates and ammonia increase is from decimation of plant matter, reducing its absorption in my grow bed.
For today, I am not feeding, and hoping I have no more deaths.

Is 80ppm Nitrates or 0.5ppm ammonia enough to have killed that many fish? Normally ammonia and nitrates read as nil.

This is my second die off, though the first was way more gradual with one or 2 fish a day, but since adding my gravity filter and salt, everything seemed to have settled, and the fish have not looked distressed. If anything, theyve been eating voraciously, and generally seemed quite happy.

do i just give up?

Nooo don't give up!!

I wouldn't have thought that is enough ammonia to cause multiple deaths like that, even with your water temps being fairly high (for Winter especially!). I will find the TAN chart for you and post it soon.

What have you used to attract the rats to the traps? That might be the more likely culprit.

Also, if the mice and rats have been eating poison baits (even if not from your house, someone in the area may be using them) the poison dehydrates them and they will search for water (which you have lots of) but more interestingly they will often seek out parsley as a way to self-medicate. If you can stop them getting to the water by using a lid, even temporarily, and stop them getting to the parsley somehow it might discourage them.

The other problem with them coming to get your parsley is that if they have indeed been poisoned, I'm guessing their droppings could contaminate your fish tank water when it gets into the growbeds. It probably wouldn't affect the levels we test for, and the only way to know might be sending the water off to be tested.

It might be worth doing a partial water change if you can. But other more experienced members might be able to offer better advice.

We all have ups and downs with AP. I have lost whole batchs of trout and lots of individual fish along the way. Also had a mouse/rat problem in the greenhouse just recently. A whole bed of green bush beans that were flowering were chewed off at the plants base. Caught a lot of mice and found this fella sucking in his last breaths after eating bait. so I wacked him with a stick. Bait is not vanishing since so I might be on top of them.
Dont know why your fish are dying

I will do a partial water change on the weekend, or if i have no fish left, a full water change.

I have not used any poison baits. The only remotely poisonous things ive ever used anywhere near my GB is multiguard which i sprinkle around the fish tank, and once a tiny amount in the GB.

Initially ive been using peanut butter as bait, but now I have some topcat non-toxic mouse attractant. Its not poisonous, and also only being used in the actual trap.

I am close to giving up.... So many dead fish, grow bed decimated, at my wits end. Will see what happens to the rest of the fish.

Mice and rats pee as they walk to leave a sent so they can find their way in the dark, their pee can cause blindness in people, so wash your hands when after you touch your media, I don’t have mice the kid has two cats, I also don’t have to many bugs running around? The cats ate them!

Even if you had no plants in the system, the bacteria would still (within reason) be converting ammonia to nitrites and to nitrates, so you'd be seeing a build up over time of nitrates but the nitrites and ammonia should still be "low"... I don't think this is what killed your fish.

Do an autopsy (necropsy) on a couple of the fish. Look for "unusual" blemishes, colours, spots, sores etc. It might give you a clue. How do the other fish look now? How are they behaving now? Are they feeding, more or less than before? Is the water discoloured? Do you have enough air? What have you changed in your system in the last week, including harvests or plantings? How old is the system? Where is the system located? Have you had any rain?

There's (nearly) always a reason why events happen, it's up to you to figure it out. Think of it as a challenge, a puzzle, a tv murder mystery.

P.S. These designs work well to contain and kill rodents... you wouldn't want a poisoned rat falling into your system!
http://www.instructables.com/id/A-BETTER-MOUSE-TRAP/?ALLSTEPS

No danger of a poisoned rat falling in my system unless someone else poisons it. I am only using attractant, not poison for the rats.

Nothing has changed for nearly a month. A month ago, I added a large gravity filter, as well as some pool salt and gradually added some kh powder to act as a buffer for PH.

I examined he dead fish pretty carefully, no noticeable marks. I dont have anything to measure DO in the water, but as there are 2 airstones constantly going, as well as a flood and drain cycle that would do the entire tank volume 2 or 3 times an hour, having 2 points where the water is exposed to air, I am assuming that is ok.

All the remaining fish seem to be ok at the moment. Did not feed them today, but yesterday,as per normal, they were pretty voracious in their feeding.

As mentioned earlier, the only thing that has changed is a significant reduction in the amount of plant matter above the tank.

Could the increase in ammonia be due to the number of fish corpses in the water today? 11 dead fish between 8 and 14cm.

It takes a little while (days) for dead fish to "pollute" the water, temperature dependent and other factors.

Is there any galvanised metal in/near the system? Could any run-off from watering or rain enter the system? I had a neighbour spray their yard with something nasty and my fish ended up wearing most of it -- any chance of overspray from a neighbour's activity?

The tank is inside a greenhouse, so not likely. I dragged a galvanised metal pole over the grow bed to get a cable across for the camera i have there now, but didnt get it in the water.

I didnt watch them eat yesterday, and noticed some food granules in the water with the dead fish. Maybe i overfed them yesterday. Pretty drastic response if so.

I just dont know. I blame the garden killer rat!

He will die!!!! Hopefully on camera tonight.

When you performed the necropsy, were the stomachs full?

I didnt quite go that far.

I just gave them a detailed external viewing.

It's a good idea to open them up and have a good look at the internals.

Even from the outside, you should have a good look at the gills, eyes, fins, tail, scales etc on healthy fish and not-so-healthy fish as it's the only way to learn what is "normal" and what isn't.

hi, I think that you should do an emergency water change, if you still have fish, I don't think that poison is the problem if it was all the fish would have died by now.

What shape are your beds? I saw some spiky rodent deterrents that are made to go along fence lines in masters today, they may work if your sides are straight?

Once you fix the problem it may feel like you have to start again, but the rewards are so worth it.

As mantis said, plenty of people lose whole batches of fish, but you've just got to pick yourself up, dust yourself off and get going again.

I'll keep my fingers crossed for you that it gets sorted out soon.


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