Backyard Aquaponics
A place to discuss aquaponics

Hey all,
I through this out on the local Facebook page here last night and got some interesting feedback, so to broaden the audience, i am posting it here as well.

These are the first batch of Perch, they growing well, no issues, feeding twice a day.

We had been noticing them darken up over the past two weeks or so and put it down to cooling temperatures.
Wednesday morning they were significantly different.
As you can see by the top photos, on the 4th of March they were lovely and shiny silver, but now they are a marbled patched camo'd arrangement.
Are perch 3 months old change colour at all?
Anybody else experience this?

Water numbers are
0 nitrate, 0 nitrites and pH at 6.5 -7.
Water temps this morning are at 15 Deg.

They are just as active and still feeding.
Just as they were in the top photo.
Both http://en.wikipedia.org/wiki/Bidyanus_bidyanus and http://fishesofaustralia.net.au/home/species/689 mention mottled bodies on juvie's but no referencing.
So i guess it is possible its just juvenile colours emerging?

Regards
Jeff

Hiya Porter, great question. I have noticed the same colour change myself, not the camo but have noticed them lighten in colour markedly. At times most are dark coloured and only a few are a noticeably lighter colour, other times all dark or all pale. I have not been able to put my finger on the reason either. They don't seem stressed and are still eating.

Hi Skeggley,

I learned the other night from he-that-shall-not-be-named-here-anymore that if Silver Perch are lightening up then there has been a drop below 6pH.
As ours hadn't lighten up meant should he be right, we hadn't had a pH drop.
As for darkening it appears that cooler temps indeed can cause this as they slow down growth in cooler months.

I also learned today that the patterning on my fish are all different, and pretty much symmetrical, indicating that it's more than likely juvenile colouring showing through.
In response to this, maybe either it hasn't been notice by others, or it only happens in certain conditions.
Our waters are crystal clear and very light all of the time, so that may have triggered the patterning as a form of camouflage and protection.
As opposed to those with less clear and darker kept tanks that the perch can feel safer in.

That is as best as i can come up with at the moment,
Either way, the are still feeding, look great health wise and still pretty active.

Regards.