Shape of growout tank, size of fry?

[jbrinker]

I have my first sucessful batch of O's to the point where they are getting their third stripe. They are about 1cm+ or so in length. Only 10 have survived from this batch, but I have another 300+ on the way - and I think I have the hang of getting them to this size now.

My question/observation is this:

A few days ago, I decided to move the 10 from the rearing tank (2.5 gal fishbowl, used as krissel) to a normal 5 gal aquarium. I moved them gently, after a couple back-and-forth water exchanges over a few hours. They all were very panicky, and for the most part "hid" in the corner of the tank for a while.

By that evening, I had placed the rock from the fishbowl in, and some were "hosting" it as normal, while others were still acting strangely. I fed, and some ate.

Next morning I found two swimming sideways at the top of the water, and several others acting very strangely - disoriented, swimming upside down or vertically. I moved them all back into the fishbowl (same water from 5g) and put things back the way they were before. Within an hour, all was normal again. They all seem fine now, and are eating again and acting normal.

Question is, what the heck was going on? Its almost as if they "don't get" what a rectangular tank is all about? Or was it just "too big" for them? Circulation was minimal, and the water was 1/2 new and 1/2 the fishbowl water.

My concern is, I have 300+ just about to enter meta. I have another hatch in 2 days (another 3-400). I'd like to move these 10 guys to other quarters, but cannot... And, I'd like a handle on how to best deal with grow-out, as the 300 will need to move from the 2.5gal much sooner than the 10 did.

Thanks for any advice...

Jeff

 

[FB]

You never said how old the 10 are just their size?

Ussually mine get moved at 4 weeks from a 5 gallon tank to a 10 gallon tank. So both of mine are square tanks.

Were they swimming into the current when displaying this strange behaviour?

FB

 

[jbrinker]

This batch was born 11/29/08, so about 7 weeks? That seems correct. I lost several entire nests in between these guys and the current "new" batch (they are on day 10 now).

The tank was filled to the top, no lid. Flourescent light about 3' away, diagonally overhead (over sink light). There was minimal current (almost none) as I didnt want to stress them too much. I just added a bubble tube, with a stream of bubbles.

FYI, I can turn off all the current in the fishbowl with no ill effects. Or crank it way up so they have to swim, it seems to make no difference.

The only think I can think of is light. The bowl is lit from above (directly) by a small undercabinet light. The tank was lit indirectly from several feet away, and competes with room lights. Perhaps they were confused? It sure didnt look good, but within just minutes of being returned to the bowl things were fine (well, they were mad, but acting more normally).

I'm certainly looking for advice, and dont really look forward to the next trial move (I will give them another few days at least)

J

 

[FB]

Did it appear that they were breathing heavily? Possibly lack of oxygen.

What kind of filtration did you have in with them?

Did you check the temperature. Possible that the bigger tank didn't hold temp like your little tank did?

It could have been stress!

FB

 

[jbrinker]

I hadn't thought about O2, however again they were "normal" as soon as returned. It was weird.

I had no filtration, just the two chunks of live rock they have lived with since hatched. I run Ammo-lock, and ammonia is at 0 regardless.

I did check temp, and was running a bigger heater. It took me a bit to get it dialed in but they were at 80F when this was going on, normally they are at 82F.

I have no doubt they were stressed - but why after 12 hours and why return to normal so fast... Weird.

I think I may get a 2.5 gal cube, and put them in that as an experiment. I also think the lighting could have confused them - if they use "light from above" as a cue. Sometime soon they will have to get out of that bowl, or I will have to buy another....

J

 

[gpsmart]

I have the exact same thing happen occasionally and I still don't know why they do it. I start mine off in a 8G rectangular tank and then shift them between 3 and about 8 weeks (depending on what else needs which tanks at the time). My grow out tanks are about 35G rectangular tanks and when they are moved to these tanks they sort themselves out and start swimming properly. I have stopped worrying about it because they always seem to sort themselves out.

If I had to guess I would say that lighting is probably the cause. In my larval tanks when they get full (I only start them off about half full) the light (8W fluoro) is only a few cm away from the fish and if they swim with their backs towards the light they will be on their side. In some positions that are shaded from the light the strongest light will probably be the reflection from the bottom and this may cause them to swim upside down.

 

[jbrinker]

I have a strong suspicion that it was lighting, since I watch their behavior in the fishbowl with no light - and they seem fairly disoriented (what little light there is with the lights off comes from the door - horizontally).

I think I will try again soon, just not right now. They are maturing nicely, all have 3 stripes now. Funny, they actually eat LESS than they did a week or two ago, almost as if they have reached a growth plateau.

I have one "runt" that hangs out on the heater - he gets picked on constantly, and as a result is the smallest. I feel bad for him, he seems to be the only outcast.

The other newer batch is coming along nicely, all ~300 are doing well and I'd say 95% are through meta and have tiny headstripes. I was hoping to move that batch to a new container soon - they will need the space. I'm thinking of a 5-gallon bucket, then a "muck bucket" when they get a little bigger.

I will probably pick up a cheap 10 with a proper hood/light for the "original 10" and see if they tolerate it better with some proper lighting.

I have a NICE batch of eggs that will hatch tonight, but I have no intention of hatching them. No where to put the larvae, and I need to concentrate on the current batch. It sucks though...