Jumping Fish

[DYIguy]

This sounds good in my head, but not sure what it would look like in real life. For a rimmed tank add a 4-6" black acrylic 'box' that fits into the inside of the rim where you'd normally put your cover- basically adding 4-6 or 8" to the top of your tank- no worries about heat or interfering with light penetration- you could also do it with clear, but black would just add visually to the rim

 

[Mark_C]

I watched a clown jump and it hit the lights hard enough to kill itself. The lights were a 8-10" above the tank.
Bought a screen, never lost another.
Couple years later I had the screen off for maintenance. As I was cleaning a dottyback jumped and I swear it hit a solid 18-24" above the waterline.
It went high enough that I had time to react, drop the tools, and catch it on its way down.
When these guys hit speed and go vertical they're like rockets.
Wondering if theres a correlation between jump height and tank depth. Is the speed burst close to instantaneous or do they need a few inches of water to build momentum?

 

[DYIguy]

I watched a clown jump and it hit the lights hard enough to kill itself. The lights were a 8-10" above the tank.
Bought a screen, never lost another.
Couple years later I had the screen off for maintenance. As I was cleaning a dottyback jumped and I swear it hit a solid 18-24" above the waterline.
It went high enough that I had time to react, drop the tools, and catch it on its way down.
When these guys hit speed and go vertical they're like rockets.
Wondering if theres a correlation between jump height and tank depth. Is the speed burst close to instantaneous or do they need a few inches of water to build momentum?

Guess my thinking may be off, one thing I've noticed- maybe you have too is when they do jump, it's in the corners, not anywhere else

 

[Mark_C]

Yeah, they have an onboard sonar system which is how they avoid rocks and such. If you look at the fish you can actually see it. Its the area on the sides and behind the head where the scales change pattern. That areas full of cilia that determine pressure changes and act as sonar, called a lateral system or a lateral line system.
When they head to the glass and make a quick left (or right), especially in 'escape/flight' mode, then they hit a corner, there's some pressure rebound from the opposing glass, so they go straight up as it's the least pressure and least likely to be where a predator is.

 

[mnat]

The new screen tops are just so easy to use and look so good, I would not over think it. My fish hit the middle all the time, so I don’t think it Would be as effective as a screen top

 

[DYIguy]

Yeah, they have an onboard sonar system which is how they avoid rocks and such. If you look at the fish you can actually see it. Its the area on the sides and behind the head where the scales change pattern. That areas full of cilia that determine pressure changes and act as sonar, called a lateral system or a lateral line system.
When they head to the glass and make a quick left (or right), especially in 'escape/flight' mode, then they hit a corner, there's some pressure rebound from the opposing glass, so they go straight up as it's the least pressure and least likely to be where a predator is.

I don't disagree about the sonar, but why does a fish that's just added to a tank swim back and forth, up and down against the glass- is their sonar off- or are they just trying to get out

 

[Mark_C]

I don't disagree about the sonar, but why does a fish that's just added to a tank swim back and forth, up and down against the glass- is their sonar off- or are they just trying to get out

It's not used to the angles of the tank or position of rockwork and is scanning to an extent, plus chemical balances and pressure throws things off in new environment.
They're scoping out the new digs and committing cilia readings of pressure changes to muscle memory.
If you rearrange the rocks in a few weeks and scare it, it'll bank around in confused circles, probably hit a corner, and go for launch.
A good party game is to give folks a cup, rearrange rock, and bang on the tank. Whoever catches the most expensive jumper wins.