197 replies to this topic

[gerald]

James -- Which pathogens/parasites can be spread by indoor-cultured snails into fish without another intermediate host?  I've been telling people that indoor-cultured snails that never had access to fish-eating bird/animal poop are "safe" in terms of parasite risk.  Bad advice?

[Irate Mormon]

Snails ARE the intermediate host.  But AFAIK only for Platyhelminthes.  But in Gerald's scenario they would be safe. 

[centrarchid]

I am not worried about snails as an intermediate host, rather I am more concerned about them as being vectors by simply being able to move between systems.

[centrarchid]

Fish are now approaching the smallest size I have seen in the wild outside of embryos and prolarvae.  Their behavior is not consistent with being planktonic.  The fish have consistently been associate with bottom and wall of tub with many concentrating around the wick.  They do very little active swimming yet have very distended abdomens.  About 10 have died thus far.  

[centrarchid]

Another note, fry have ability to approximate tone of background.  While swimming over dark background they are dark while over light back ground they blanch.  Change appears rapid not unlike centrarchids are capable of.

[centrarchid]

Images I take are not very good.  You will have to suffer with me on that.

 

Sock is being used as wick.

 

 

 

[mattknepley]

Very, very cool!

[gerald]

Thanks for explaining about the sock.  I figured you were holding fish in shoe boxes and just forgot to take out the shoes and socks.

[centrarchid]

Fish nearly doubled in size since last post.  Somehow they disperse themselves evenly about the tank.  Socks made of good material for wicking action and are sufficiently broad to provide needed flow.  Water level in tank gives 1.5 inches of free-board.

[centrarchid]

Doing a Little Experiment.

 

Student noted fry appeared to be disappearing based on observations when feeding with BS.  We did a little looking around to find fry are stacking up in shadow of wick.  I suspended a black nylon screen rolled into a tube just under the water surface.  By tomorrow I bet most fry will be inside or under the tube .

[centrarchid]

Some, about 30, fry moved to tube suspended at surface in middle of tank.  Still concentration of fry much higher under wick.  Fry also starting to get really big bellies.

[centrarchid]

Overall, the pirate perch fry are very different from fry of all other species I have reared.  Firstly, neither vision nor direct contact enabling taste appears important in orienting on and capturing prey.  Like catfishes the pirate perch can detect food items behind them.  Relative to all other species they move very little when hunting for eats.  Most species at least initially move about consistently in their environment to encounter prey.  For the most part the pirate perch sit and wait.  Like gobies and some cichlids the pirate perch fry orient the ventral surface towards whatever structure they are near although the pirate perch do flip over to upside down position.

[centrarchid]

A very interesting note.  One of the females appears ready to produce her third clutch this season.  She has eaten very little.  Her tissues must be nearly water to support all that vitellogenesis.

[centrarchid]

Fish starting to distribute themselves evenly throughout tank.  Only near surface do they seem to avoid.  Density under wick going down.  It appears they are starting to get more inclined to engage each other antagonistically or at least from a greater range.

[centrarchid]

Fish getting big enough to see details.

 

 

 

[centrarchid]

Tonight I observed fry after timed lights went off.  Fry dispersed more, higher in the water column.  They are also darker.

[centrarchid]

Another change.  During day fry either near bottom of tank or they stack up under the black cylinder shown above.  This was an abrupt change from yesterday.

[centrarchid]

Lights off now resulting in another boring observation.  Fry exhibit a lot more forward movement at night.  Night time they move forward much more frequently.  They have also moved up into the water column thus are more uniformly distributed throughout the tank.

[centrarchid]

Prepared to be in awe.  Look at these evil little pirates.  Uniform in size and with pot bellies.  They are echo locating little beasts using passive sonar as well.  Most are within 4 inches of surface.  They are pushing 3/4 inches total length.  Still being fed Artmia sp. nauplii although could handle water fleas with ease if cultures would take off.

 

 

 

 

 

 

[centrarchid]

Also note the very large opercular region  That massive head must be important for something.