Backyard Aquaponics
A place to discuss aquaponics

OK guys, somethings seems to be up here with my silvers. I've had 5 silver deaths in 5 days! Not good! I thought maybe I was over feeding my fish, but I have had no spikes at all in readings. 20deg, 0 ammonia (barely changing colour), 0 nitrites and ph 7.4. Once again in my aquarium days this was perfect. I'm feeding them about 2 teaspoons of crushed organic pellets ( they're a bit big for the fish if I don;t crush them, they try to suck them in but don't get far and spit them out) I have tried to avoid getting too much food dust into the system, but I am sure a little gets in. The dead fish look healthy, no spots, blood or noticable fungi. Good colour, darkish grey skin. Checked out stomach contents and couldn't find any sign of food in them. I did find a blackish sac (?) which I popped and greenish black stuff came out so not sure what that is. The fish that have died have been the smaller ones of the pack so maybe there are starving? If I get anymore death I'll take a photo (hopefully won't have to) as I say they all look healthy and are feeding pretty agressively! All I can think is the runts aren't getting to the feed in time and have been missing out at breakfast and dinner time! I do also have been putting in a lettuce leaf and brocoli leaf each couple of days for snacks and have been doing that for about 2 wks.

Any thougths?

Quachy

Food could be a problem, are they dead with mouths wide open?

2 teaspoons for how many fish?

Yeah two were. I did crush the food down to a pretty fine crumble. There were 30 fish, now down to 25 all ranging from 100-140ish mm.

Well for starters, I dont think two teaspoons for fish that size is enough, they would not be getting any food.

How are your water temps? If it is starting to spend a bit of time below 20 deg c, you will loose the weaker ones. There is usually a run of deaths heading into winter, then some late winter.

So how much food then 3-4teaspoons?

Water temps range between 17-23 deg.

Quachy

At least.

General guideline is to feed them as much food as they will take in 15 minutes, twice a day. This will show you the average of what they want.

I use the auto feeder to then supply this amount of food every day, over 4 feeds = no deaths, excellent growth.

However, if the other fish are doing ok, and growing fast, there may just be a genetic problem with the smaller fish, however I feel this is unlikely given their size. Most abnormal fish tend to die before 50mm in size.

My thought is along the same lines... fish can survive being underfed for a fair while, but eventually they just die. Those fish should be on a 2.7 or 3mm pellet. I usually feed until the first pellets hit the bottom of the tank ie the fish ignore them, then stop.

open mouths often suggests lack of DO, but if you only lost the runts, and aren't losing any more, then I'm inclined to agree it's lack of food.
Try spreading the food around the tank a bit, also feed a little more. If using floating pellets you can feed too much, then remove the excess.

whats your areation like, my system is 10000 litres, and im running 10 air lines, temp at the moment 19 deg, no problem

I'm hoping that my DO is OK, I have a spay line constantly going into the tank, so always have some kind of air happening and when the gbs drain, then I get a bit of O2 into the tank. Maybe I need to invest in some air lines?

Had a couple more today looking a little unhappy, not swimming around as fast as the others, in fact I was able to very very easily net them. They looked healthy on the outside and one was a bigger fish as well. Don't know what is going on!?! I'm going to put salt into the system, so far no salt at all (well at least I haven't put any in yet). Will drop some in tonight and see how they go in the morning.

Quachy.

Just checking that to get to 5ppt for a 1000lt system, I will need to put in 5kgs of plain table salt?

Quachy

Sea salt. Or sunray pool salt. Non iodized.
1kg per 1000ltrs

Just chucked in 1.5 kgs of sea salt, 1kg of rock and 500g of table. So if I have a 1000lt system, then I'm assuming that I have done a 1.5ppt treatment. Will see if this helps by the morning. I will buy another 5 or so kgs of sea salt. Bloody hell it does seem like a hell of a lot of salt to chuck in!

Quachy

1.5+1+.5=3kg in 1000ltrs is 3ppt(parts per thousand ltrs)

Pool salt is cheap in the 20kg bag for $7 ish.
Did the table salt have anything else in it?