Aquaponics: Things that go Crunch in the Night!

Have you ever got up in the morning, went to inspect your aquaponics system and discovered something has been nibbling at your seedlings?

A comment by Catryna today inspired this post.

“My main interest in Aquaponics is that our family lives in the rurals of San Diego county, California.” she said.  “The rodents underground and above ground decimate anything you grow and that includes fruit trees. So, having an Aquaponics system enclosed in a greenhouse is a win/win system; no access by the critters and year round food and fish. You can’t beat it.”

Well our system is not under cover. Its out in the open in a courtyard but enclosed by the house, gate and fence. But just a few weeks ago I also began noticing that the fresh new seedlings I planted out the day before were all neatly cut right down to the base of the stalk the next morning. Something was out in the night munching and crunching on our seedlings.


I immediately thought it might be a stray possum. We have seen them occasionally at night moving around in the trees leaping from branch to branch. Some people are then forced to put chicken wire over their growbeds to protect their crops. But really – who wants to do that?!

I decided to make the possums life difficult to land on our tanks by trimming any over hanging growth from touching our fence, making life more difficult for the little critters from landing on the fence, scurrying down a rope and into the grow-bed. Surely this would solve the problem by eliminating any way for them to easily reach the fence – I thought.


"Apart from a green tree frog sitting on the autosiphon everything else looked okay."

I replanted the system with some nice succulent Cos Lettuce convinced that the problem was now solved. The next day every one of the dozen seedlings was trimmed off straight down to the base like the little blighters had mini chainsaws rather than incisor teeth!

I looked around the fish tank and growbeds trying to figure out how these creatures were getting in to the beds. The grow-beds are at waist level. They thief would have to either abseil from the roof down or use grappling hooks to climb up.

I put away any stray box, bucket or bin under the beds to eliminate any structure they could climb onto. Even power cords from the fish tank were examined. I had visions of these creatures like circus tightrope walkers doing their thing at night.

Nights became a mission of patrolling the system at night with flashlights like one of those NAZI camp guards looking for signs of infiltration. But apart from scaring the fish with the light beam and causing them to crash and leap around in the tank, no sound or movement could be detected.

Only the sounds of chirping crickets and the moon peeping from behind the cloud. It was getting quite mysterious.

The next morning with more lettuce eaten I decided to take a forensic look at the lettuce. I examined the way the thing had been eaten. Top growth of the lettuce was okay. The bottom leaves and the most tender side leaves where nibbled on. I began to suspect Rats in the Grow-bed.

Poisons were ruled out but I could use a bit of old fashioned technology.  The old trusty rat trap with a bit of bait on the end.

I placed a few traps around the side of the fish tank and one in the grow-bed just for fun.

Revenge will be mine. It will be sweet.

I slept well that night.

The next morning I examined the grow-beds. Nothing had been eaten. Apart from a green tree frog sitting on the auto-siphon everything else looked okay.

Nothing had been touched.

The fish looked happy and hungry. I looked around the sides of the tank. One trap was still set and untouched.

The other trap had caught a large rat.


Ouch! Right across the nose too!

I left a few more traps set for the weeks ahead and only caught another one. For the rest of the time, the rat menace had abated. How they managed to climb up the beds – I’ll never know. Some people tell me rats can form a rat pyramid and climb on each others shoulders. Some say they can jump pretty high. However they did it will have to remain a secret that they take to the grave with them for my grow-beds now are undisturbed.

The tomatoes are booming and the lettuce is growing well and there is no more things that go crunch in the night in my little part of paradise.

However – spare a thought for all those people and tourists that occasionally visit Sydney!

Don’t sleep on the park bench.

What creatures disturb your grow-bed?