Carpet surfing.
You'd be amazed at the ability of some fish to find the tiniest hole out of the tank.
And you ask yourself why would they?
4 things make jumping more likely:
a. shallow tank
b. a fish that has not yet established a territory and found a hole to spend the night in.
c. strong upwelling currents from tank circulation.
d. bullying by another fish
When a fish feels threatened, it can a) run far and fast. b) head down to its night-hole c) head up as fast as it can---and it will take any upwelling current. If none, it will still rise as fast as it can and jump, which confuses a pursuer and breaks the 'trail' it may be following.
This works in the ocean. It does not work in a tank.
And then you get a few species who just like to ride a current for the heckuvit---with bad consequences.
How do they find the holes? your water lines do that: the same water lines that create the current they're following. That's one. Use a scissors and Gutter Guard or plastic needlepoint canvas (hobby store, needlework store) to create very tight screening over downflow (a little overhang is good---and tipping the screening back toward the tank is good, so the wayward fish can flop his way back into the water easily.
I have a 9" fake rim on my tank, with Gutterguard duct-taped wherever hoses enter; I have needlepoint plastic canvas over my downflow. I have not had successful surfers, and I keep a dartfish in an open-topped tank. Dartfish (firefish, gudgeons, etc) are among the most frequent [and highest] jumpers.
Always be careful in introducing such a fish---be sure you introduce them in plenty of time before lights-out, early in the day, so that they can find a hole for the night. The most likely jumper is a fish that does not see safety as 'down'. Spook my tank, and every fish in it will go 'low', not up. That's because a) the tank is 20 inches deep in water-depth. b) I have really holey rockwork and c) my fishes all have their night-dens.
Hope that helps with understanding this problem. Some fishing line for stitching, duct tape for creating good seams, and attention to detail can save your fish. Some fish, because of the angle at which they leave the water---notably firefish/dartfish---can find the holes in eggcrate, so be advised. They go up like a missile, and chances are good they'll locate a hole. Once up, they'll flop along the surface of the grid, but their shape doesn't let them go back through, and the hot lights don't help.
So try to head them off from jumping in the first place; I've found 9" is a pretty good number: my fishes can't get enough running-room in my tank or enough energy from the upwellings to exceed that height.
So far.
You'd be amazed at the ability of some fish to find the tiniest hole out of the tank.
And you ask yourself why would they?
4 things make jumping more likely:
a. shallow tank
b. a fish that has not yet established a territory and found a hole to spend the night in.
c. strong upwelling currents from tank circulation.
d. bullying by another fish
When a fish feels threatened, it can a) run far and fast. b) head down to its night-hole c) head up as fast as it can---and it will take any upwelling current. If none, it will still rise as fast as it can and jump, which confuses a pursuer and breaks the 'trail' it may be following.
This works in the ocean. It does not work in a tank.
And then you get a few species who just like to ride a current for the heckuvit---with bad consequences.
How do they find the holes? your water lines do that: the same water lines that create the current they're following. That's one. Use a scissors and Gutter Guard or plastic needlepoint canvas (hobby store, needlework store) to create very tight screening over downflow (a little overhang is good---and tipping the screening back toward the tank is good, so the wayward fish can flop his way back into the water easily.
I have a 9" fake rim on my tank, with Gutterguard duct-taped wherever hoses enter; I have needlepoint plastic canvas over my downflow. I have not had successful surfers, and I keep a dartfish in an open-topped tank. Dartfish (firefish, gudgeons, etc) are among the most frequent [and highest] jumpers.
Always be careful in introducing such a fish---be sure you introduce them in plenty of time before lights-out, early in the day, so that they can find a hole for the night. The most likely jumper is a fish that does not see safety as 'down'. Spook my tank, and every fish in it will go 'low', not up. That's because a) the tank is 20 inches deep in water-depth. b) I have really holey rockwork and c) my fishes all have their night-dens.
Hope that helps with understanding this problem. Some fishing line for stitching, duct tape for creating good seams, and attention to detail can save your fish. Some fish, because of the angle at which they leave the water---notably firefish/dartfish---can find the holes in eggcrate, so be advised. They go up like a missile, and chances are good they'll locate a hole. Once up, they'll flop along the surface of the grid, but their shape doesn't let them go back through, and the hot lights don't help.
So try to head them off from jumping in the first place; I've found 9" is a pretty good number: my fishes can't get enough running-room in my tank or enough energy from the upwellings to exceed that height.
So far.
