We all know that fishes live in water. Therefore, for fishkeepers, the normal tank to keep them in would be an aquarium or a pond. These tanks hold water where the fishes can live properly, and these enclosures let us enjoy them.

Unfortunately, on some occasions, some fish manage to get out of their tanks and die. Finding your fish dead on the floor is a nightmare each fishkeeper dreads waking up to. Thus, it is very important that we keep the fish in their tanks and prevent them from getting out.

Surely no fishkeeper would wish this kind of tragedy to happen to the beloved fish they are caring for. But accidents do happen and this is part of the fishkeeping hobby. As responsible fishkeepers, it is our duty to prevent accidents such as these from happening.

Through my many years of fishkeeping, I can only think of three ways a fish can escape a tank: jumping, slithering, or breaking out. By creatively figuring out ways to address these three causes of escape, a fishkeeper can prevent disaster. Additionally, knowing what kind of fish you have will help you make your tank escape-proof.


This is the number one method for fish to escape from a tank. I am sure we have all had a fish jump out from our tanks, with tragic consequences. You may find it dead on the floor, or if you’re lucky, you’ll find it still alive, but will not recover from the injuries it sustained and will eventually die later.

Maybe not all, but fish do jump. As fishkeepers, it is better to assume that whatever fish we have will jump. There are many ways of preventing them from jumping out of the tank.

The best way is to use a glass cover of the right size and thickness for your aquarium. Unfortunately, ever since I got into fishkeeping—which was decades ago—locally manufactured, ready-made aquariums have the most useless glass covers. All such aquariums from 2.5 gallons up to 100 gallons are equipped with undersized glass covers in terms of size and thickness. Depending on the size of the aquarium, they always leave a gap of 2 to 6 inches once you affix the glass cover. To compound the problem, the glass cover is usually a puny 1/8 inch thick, which easily can be broken by a modest sized fish.

Until now, it blows my mind why our aquarium manufacturers cannot provide the right sized tank cover for the aquariums we pay good money for. Normally, in all the excitement, you go home and set up your tank only to find out that there is a big gaping hole that the tank cover leaves behind, and this is such a letdown because you know your fish can jump out of its own aquarium.

Therefore, when buying aquariums, make sure you specify a glass cover that will completely seal the top of the tank. If you are buying from an aquarium manufacturer, then you can request this and they can cut a glass cover specifically to your needs while you wait. You also might as well specify a thicker glass cover. If you are keeping a fish bigger than 6 inches, better get one that is thicker than the standard 1/8 inch glass cover.

With imported aquariums, don’t be fooled by those fitted with hoods. I experienced thinking my tank was fully covered by the hood. The next day I found all my Rainbow Snakeheads (Channa bleheri) on the floor. Yes, the hood covered the entire top of the tank, but upon inspection, the plastic lid where you feed the fishes was so light that it didn’t keep them in the tank when they jumped. They easily escaped through the lid so I had to put adhesive tape just so they couldn’t break through it. Therefore, it is very important that the tank cover is a bit weighty and not light and thin, because a fish may lift the cover when it jumps and escapes.

As mentioned earlier, it is best to assume that whatever fish you have will jump. People are quite aware that Arowanas are good jumpers. Thanks to the Arowana’s popularity, fishkeepers often talk about the Arowana’s jumping prowess. Personally, however, I rank the Arowana as just an average or good jumper. I have kept some fishes that are better jumpers than Arowanas by literally leaps and bounds.

Torpedo-shaped fishes are very good jumpers. The streamlined, hydrodynamic body is built for speed. They swim very fast underwater and when it is able to break the water surface, it flies through the air and across the room. The Goliath African Tigerfish (Hydrocynus goliath), Golden Dorado (Salminus brasiliensis), Bala Shark (Balantiocheilos melanopterus), African Pike Characin (Hepsetus odoe), and the Freshwater Barracuda (Ctenolucius hujeta) are just some fish that fall in this category.

I remember a time that I personally witnessed a fish flying through the air and across the room from a single jump. We were closing a fish show in a mall in Makati, and as we were about the scoop up a Golden Shark (Leptobarbus hoevenii) with a net, this 20-inch monster jumped out over everyone’s heads and landed about three stores away. That jump could have won the Philippines a gold medal in the recently concluded Southeast Asian Games!

As if disbelief is the norm, it seems unbelievable but Bichirs are very good jumpers. With a long and heavy body plus small fins, how can this fish—which seems anatomically unsuitable for the job—be able to jump? To think the Ropefish (Erpetoichthys calabaricus) is a Bichir, only much longer but equally agile with its fins; that’s much more difficult to believe. But believe is something we, friends from the Philippine Bichir Brotherhood, do.

Bichirs are very good jumpers and they love doing so. A thud coming from the Bichir hitting the glass cover is a sound we all are accustomed to. We are so used to hearing it but aren’t bothered because our tanks are well covered. But we hear that all night long.

As if coming from an episode of Ripley’s Believe It or Not, I once observed my Polypterus weeksi do the unthinkable. Knowing for a fact that Bichirs are very good jumpers, my Bichir tank was fully covered. However on the left brace of the tank, I had 1-inch diameter holes made where one of the three was used to secure the return pipe from the sump. The other two holes were left open and used for feeding, etc.

I was just watching the fish swim about in the tank when I noticed this particular P weeksii was just suspended in mid water, head obliquely pointed up and tail down. This is queer since Bichirs spend 99% of their time resting at the bottom. Suddenly, the P weeksii contracted its body and jumped out of the water and through the 1-inch diameter hole! It was aiming at the hole the whole time it was suspended! To think they are said to have poor eyesight. They are not just good jumpers, they’re very smart too.

Snakeheads from the genus Channa and Parachanna are some of the greatest jumpers of the aquarium fish world. I never, even for one second, leave their tanks uncovered. If you have just bought a couple of snakeheads and are actually releasing them from the bag, be very watchful, wary, and careful because before you can release the last one, the first one may already have jumped out of the tank!

Never underestimate how cunning a snakehead is. Local lore has its own stories of the legendary “Dalag,” “Bulig,” or “Haruan” jumping out of the lake and travelling to the next body of water. I too have a tale quite difficult to believe. I bought 10 pieces of Golden Snakehead (Channa stewartii). As it was an impulse purchase, I didn’t have a tank ready for it, so I cleaned out a 75-gallon tank and put in water from the pond. I released the C stewartii in the tank, which only held 3 inches of water. Confident that these wily Snakeheads could not jump out, I hurriedly left the house.

The next day I was so surprised not to find a single Snakehead in the tank. All ten of these 5-inch fishes were able to jump clear over the 19-inch wall of the almost empty tank—they all managed the Great Escape!

The lesson here is to cover the top of your tank. Cover, cover, cover. Check the gaps between the glass cover and braces. Cover the holes on the overhead filters and trickle filters. Improvise ways to efficiently cover the area where the inlet and outlet of the canister filter is located. Observe if the space provided for the air hose is too wide for the fish to jump through. Never leave anything to chance because if your fish gets a chance, just one chance, then it’s a goner.


Not as common as the previous cause, this is nonetheless a major concern as well. If they can’t jump, they will surely slither out. Limited to eels, and to some extent, rays, this method of escape can be mind-boggling to prevent.

Good thing locally manufactured aquarium designs have inadvertently solved this problem in a big part. Locally made tanks have top braces for strength and support. These braces surround the top and thus form a ledge covering the top, preventing eels and rays from slithering out of the tank.

But never let your guard down. No fishkeeper is smarter than an eel when it comes to finding an escape route from your tank.

A friend told me his story of his Tire Track Eel (Mastacembelus armatus) that escaped the tank that he thought he had secured very well. The top was fully covered. He had specially made glass covers that fitted the entire top. All holes in the overhead filter were also covered. Yet one day he couldn’t find his Tire Track Eel in the tank. He looked all over and could not find the eel on the floor. After giving up, he decided to clean his overhead filter. Lo and behold the small eel was nestled in the chamber. This little critter was able to slither its way up the return pipe of the overhead filter and into the chamber! Since eels love to swim against running water in rivers, the eel was attracted to the flowing water from the return pipe of the overhead filter and the Marmatus was able to swim up the pipe and into the filter.

Another story from another fishkeeper with a similar eel, the Fire Eel (Mastacembelus erythrotaenia) found its way to the sump filter by slithering up the overflow pipe. This eel eventually slithered out of the sump and on to the floor. When the owner saw it, the eel was already dried up.

Another fishkeeper invited me over his place to show off his 20-inch Freshwater Morey Eel (Gymnothorax polyuranodon). The first I noticed was his tank had braces only on both ends. I knew right away it was trouble and by the time we looked in the tank, the eel was no longer there. A frantic search found the eel dusty and covered with muck. My friend felt terrible. Good thing I suggested that the eel might still be alive and we rushed to clean it up. Luckily, it survived.

Rays, on the other hand, are not as athletic as eels, but if the tank is filled to the brim and the clearance is just a few inches, it can slither out. The brace on the top of the tank is a good way of preventing rays from climbing over the tank. If you have to keep rays in a tub, then you must lower the water level to about 10 to 12 inches from the top. This should prove to be a clearance high enough for it to be unable to climb out.


Some fish we buy as little cuties from fish stores grow up to be huge monsters. Fishes like the Red Pacu (Piaractus brachypomus), Redtail Catfish (Phractocephalus hemioliopterus), Tiger Shovelnose Catfish (Pseudoplatystoma fasciatum), Alligator Gar (Atractosteus spatula), Giant Snakehead (Channa micropeltes), and Arapaima (Arapaima gigas), among others, are sold in shops at a few inches in length. After some time, they grow to be very, very big.

These “tank busters” are not just big, they are also so strong, they can literally bust their tanks. Locally manufactured, ready-made aquariums are made of thin glass panes. The bigger tanks, namely 75-gallon, 90-gallon and 100-gallon tanks, are made of glass with a thickness of 1/4 inch. The smaller tanks are made of even thinner glass panes. While we are able to keep these fish in these tanks, some are able to break their aquariums. These tank busters need bigger, stronger tanks than what is commercially available.


In closing, we fishkeepers must be reminded that fish only do things that come naturally to them. Some fish will jump; some fish will slither; and some fish can break their tanks. Fish can escape from their tanks. This can happen to both newbies and veteran fishkeepers. Let us all take the extra precautions and actions to prevent these from happening. After all, we all love seeing our fishes swim happily in their tanks…and not on the floor.


Read more about fish tanks here:


This appeared in Animal Scene magazine’s October 2017 issue.