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Cory Crumbs by Eric Bodrock
System "A"     System "B"    Feeding and Diet

What are Cory Crumbs? Well, for years now friends have been telling me that I should write down some of the experiences I've had spawning and maintaining Corydoras catfish. I started breeding Corys when I was pretty young, I’d say close to 30 years ago around the age of ten or eleven! To date I have spawned and raised fry of approximately 35 different species. I’m going to sit down someday soon and make a list of them. Anyways, Cory Crumbs, has no rhyme or reason to it's layout or design, it's in no specific order, is just my observations, ideas and random thoughts, “crumbs” of information on Corydoras catfish. I hope that someone out there finds something useful in all of my ramblings that helps out with their Cory keeping and breeding attempts.

When I was younger, all my spawns were done in individual aquariums. In the last couple of years I have designed some “mini” central filtering systems to house some of my breeding colonies. This cuts down greatly on the amount of time needed to do water changes and maintenance in the fishroom. As you read on you’ll see “System A” and “System B” mentioned and I go on to explain how those systems are set up. A really neat thing happened in these systems. Purely by accident, I found that when a group of Corys started to spawn, it produced a domino effect though out the whole system, triggering other colonies to throw eggs. I guess it must be the release of pheromones, enzymes, hormones or whatever into the water.

Please keep in mind as you read on that I am just a hobbyist. Not a scientist, doctor or collector/explorer in South America and most of all NOT an English Professor. As you will probably find out as you read on; I ain’t a good righter cause sum a the stuff I does knot the way its ought be! …….. Remember, A Hobbyist!  

 SYSTEM “A”  This system contains two rows of eight, 20-gallon high aquariums, 24”x12”x16”. Water capacity about 260 gallons. They are positioned with the narrow end facing to view to save space. Each one is drilled and fitted with a 1” overflow standpipe that keeps the water level near the top trim. Each tank on the top row empties into the tank directly below it on the bottom row. The undersides are painted black as to not allow any light to enter from underneath. It would not be natural for the fish to have light under them and most likely cause them stress! The backs of each are also painted black. As the water level in the bottom row of tanks overflows, it drains into a 40-gallon breeder aquarium (36”x18”x16”) that is used as a filter/sump for the whole system. The dirty water, when it drains into the filter, first runs thru “pre-filter” foam that traps the larger pieces of dirt and waste. Then, the water drips thru a plastic plate with holes and passes thru approximately 26 gallons of bio-balls for biological filtration to remove ammonia and nitrites.  A section of the filter is divided off and used as a sump. An external pump, approximately 1200-gallon per hour, pulls water from the sump and pumps the clean water back to the top row of aquariums. Each of the eight top row aquariums has a valve to regulate the return water flow. Water flow is rather swift. In addition to the central filtering system, each tank has a sponge filter in it. This acts as a back-up filter if I have a problem with the central and if a tank is shut off the system it will still be filtered. A drain, with a valve, is located under the bio-balls in the filter. This makes water changes simple. Water changes of 40-50% are done every 7-10 days and the pre-filter foam is washed out. Tap water is added straight into the sump with the addition of a commercial de-chlorinator. The pH of the system ranges from about 6.0 to 6.8 between water changes. I also periodically check the systems total dissolved solids (TDS) that stay pretty close to 230 ppm. My tap water pH averages near 7.4 with a TDS of 240 ppm. Room temperature I can adjust as desired, but normally kept in the low to mid 70F. Each aquarium is fitted with a glass cover. Fluorescent strip lights run over each of the aquariums. Each tank houses only one spawning group of Corydoras catfish. A clump of bare root Java Fern, Anubias or Java Moss, along with a sunken mop (made of 100% acrylic yarn) is added to each breeding colony for hiding places and a spawning surface for some species. Both sides and the front glass of the aquariums are cleaned regularly. I leave the glass dirty on the backside of the tank for two reasons; (1) In hopes that this may help deter the Corys from laying eggs on a dirty surface (I think it works!) and (2) It is hard as heck to reach! There is no ultraviolet sterilizer used on the system. Any colony of fish added is always quarantined before being introduced to avoid any diseases. I also believe that since no ultraviolet sterilizer is used and all the water is common throughout the system, when I group spawns they release pheromones or enzymes that trigger other groups to spawn. May times I have seen that within a day of a spawn several other groups throw their eggs, sometimes within hours and as long as two days later.

Click here to view diagram of "System A"

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  SYSTEM “B” This is a central filtering system that holds approximately 110 gallons of water. The main row holds six fifteen-gallon aquariums, 24”x12”x12”. They are positioned with the narrow end facing to view to save space. Each one is drilled and fitted with a 1” overflow standpipe that keeps the water level near the top trim. The undersides are painted black as to not allow any light to enter from underneath. It would not be natural for the fish to have light under them and most likely cause them stress! The backs of each are also black. Each aquarium has a tightly fitted glass top. Return water from the filter enters in the back left corner via 5/8” hose. As the water level in the tanks rises from the return, the water overflows and empties into a thirty-gallon aquarium (filter/sump) located under them. This thirty-gallon is divided in the middle. The right half houses a breeding group of Corys. The left half acts as the filter chamber. As the water flows into the filter chamber it first passes over a thick foam sheet that acts as a pre-filter. This pre-filter catches the larger pieces of waste and junk in the water. It is important to keep this clean, with regular rinsing. The water then passes thru approximately 7 ½ gallons of bio-balls. This is the biological filter where ammonia and nitrites are removed. A small section of the filter chamber (sump) holds a 600-gallon per hour submersible pump. This pump pushes the water back to the main row. Each tank has its own valve to regulate water flow. In addition to the central filter, each tank has its own sponge filter. A bulkhead was installed under the filter chamber with a hose and valve as a drain for water changes. Single strip fluorescent lights are used overhead. Each tank houses only one species of Corydoras. Several clumps of bare root Java Fern, Anubias or Java Moss along with a sunken mop (made of 100% acrylic yarn) provide hiding places and a spawning surface for some species. Water changes of 40-50% are done every 7–10 days. Water is replaced straight into the sump from the tap with a commercial de-chlorinator added. The pH of the system ranges from 6.0-6.8 between water changes. I also randomly check the total dissolved solids (TDS) that stay around 260 ppm. I’m not sure why, but this is a bit higher than in system A. My tap averages a pH near 7.4 with a TDS reading about 240 ppm. Both sides and the front glass of the aquariums are cleaned regularly. I leave the glass dirty on the backside of the tank for two reasons; (1) In hopes that this may help deter the Corys from laying eggs on a dirty surface (I think it works!) and (2) It is hard as heck to reach! There is no ultraviolet sterilizer used on the system. Any colony of fish added is always quarantined for at least several months before being introduced to avoid any diseases. I also believe that since no ultraviolet sterilizer is used and all the water is common throughout the system, when I group spawns they release pheromones or enzymes that trigger other groups to spawn. May times I have seen that within a day of a spawn several other groups throw their eggs, sometimes within hours and as long as two days later.
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  FLAKES & PELLET FOODS -- As with any type of fish, the more their diet can vary the better. In today’s market place there is a huge selection of flakes/pellets available. I prefer to use a specialty formula such as earthworm, spirulina, plankton/krill/spirulina (PKS), cichlid, or shrimp and rotate variety with every feeding. If you have a central filtering system or use a power filter, feeding flakes can be tricky. One must add the flakes so that the food doesn’t simply get pulled into the filter. You can shut the filtering system off or what I would do is put the flakes in a separate container of water to get them soaked and wet. In a few minutes the flake will be soggy enough that they will sink to the bottom of the tank. You’ll still have a problem if there is good water current. The answer there is to stick with a pellet food. Most of the above mentioned dry foods also come in a pellet form. Pellet foods are what I use with adult breeder in my central systems. For fry and younger fish, I’ll crush the flakes into a powder and feed several times throughout the day.

 FREEZE DRIED (FD) FOODS – I would say that the single BEST dry food for conditioning any of the Corydoras into breeding would be FD Tubifex Worms. These are commonly sold in a cube form. Feeding is very easy and works well even with a central filter or power filter. I take a few cubes and pinch them between my thumb and two fingers. Then submerse into water and squeeze several times to get them water soaked. If you roll the cubes a bit while you are squeezing they will wet throughout nicely. Try to get them to the point where you can’t feel a hard lump in the middle. Then pull them out of the water and try to squeeze all the water out of the mass/ball for a couple of seconds. When you drop the mass/ball into the aquarium it drops right to the bottom. After you have fed your Corys like this a few times they will learn to “attack” the worms in a feeding frenzy…provides great entertainment! (OK, so I live a dull life!). Even younger Corys, at 1cm in size, will eagerly accept the Tubifex Worms.
Most other freeze-dried foods don’t work well with Corydoras. The problems being that the foods float or are too large for them.

 FROZEN FOODS – Such foods as Bloodworms, Tubifex Worms, Brine Shrimp, Mosquito Larvae, Daphnia, Cyclops and Baby Brine are available in frozen forms. I use frozen Bloodworms with my adult and sub-adult Corys on occasions. First I thaw them out in cool tap water in a plastic container; (fish in nature have never eaten an ice cold “frozen” meal before!). Once thawed, they will sink to the bottom. Then a use a cooking baster to suck up the worms and squirt them onto the bottom of the catfish tanks. Because they are heavy, they will stay pretty much on the bottom until the fish can eat them up. This will work with other heavy bodied frozen foods, but the overflow of my central systems will pick anything light, such as Daphnia, Cyclops or Baby Brine. If an undergravel, sponge or box filter is used any of the frozen bite-sized foods work well. I have experienced/or noticed that when I feed frozen Cyclops to younger (under 1cm) Corydoras fry a couple always turn up dead the next day. I speculate that the shells of the Cyclops or the amount that they eat may be the problem. People have told me that newly hatched Baby Brine Shrimp will cause a digestive problem with fry, both from the shells & salt content, but I have not seen this to be a problem at all. I do rinse, soak or thaw any frozen or live foods before I feed them off. Better to be safe than sorry!! Adult Brine Shrimp, frozen or live, I wouldn’t recommend to use. From all that I have heard and read over the years, it isn’t a very nutritional food unless it has been “gut-loaded” and even then I have my doubts. 

  LIVE FOODS --Without question, the very BEST food that can be fed. But, there are problems that can occur from this. First, I’ll say that live BLACK WORMS, also sold/seen as “Trout Worms”, work as a miracle, wonder drug for getting Corydoras into outstanding breeding condition, not to mention most other types of fish too! But I’m also convinced that these worms can introduce disease to your fish. The reason I say this is that at the end of 1999 and into 2000, I developed a problem where I was losing a bunch of Corydoras, mostly younger fish and sub-adults. I won’t waste time here with all the terrible details of the problem but it was a stumper to me! I discussed my problem with people such as Ian Fuller, Shane Linder and many others and couldn’t put my finger on the exact problem. One of the things I did, along with massive water changes and medications, was that I stopped feeding live Black Worms completely. In several months, all the symptoms of the problem went away, but I don’t know for sure what the “cure” was. I have heard of Discus breeder that wouldn’t touch a Black Worm for fear of diseases! I think they might be right. BUT WAIT! …. I don’t think it is the worms themselves that is the problem! I suspect the poor conditions that the worms are exposed to be the problem. If you have ever seen a shipment of these worms come in, they CAN be horrible! Warm, no air, water that looks like blood red mud………THAT‘S THE PROBLEM!!  Be aware of the quality of the worms you receive.  If you do get a batch that looks good, make sure you keep them as clean as possible or you may have some problems. About six months after the problems I experienced were gone, I resumed feeding small amounts of well cared for Black Worms to only my breeding colonies of Corys. Spawns are now back to being larger and more frequent, and man do they go crazy over those Black Worms!

If I have time I will occasionally chop up some live RED WORMS for the adult Corys. Good food but time consuming and a bit messy. Live TUBIFEX, if you find them, are probably more risky than the Black Worms with the diseases. The FD Tubifex Worms work just fine.

 WHITE WORMS are excellent foods but very rich. Mixed in the diet they prove to be a great supplement. I don’t have good success raising these so I don’t feed them. I have in the past, but not in recent years. GRINDAL WORMS are the same way. I always end up with a tiny fly infestation in my cultures so I haven’t had these in a while either.

Other live foods such as Mosquito Larvae are good food but they hang near the surface and the Corys, spending most of the time on the bottom, might not get them at them. If the Corys don’t get them, they get you! Daphnia is also a good food. They swim in open water, which gives the Corys a challenge to catch. These work great if you’re going out of town for a longer period of time, the Corys won’t be able to eat them all at once so they’ll last for a while.

As I had stated earlier about live adult Brine Shrimp, I wouldn’t recommend using it. From all that I have heard and read over the years, it isn’t a very nutritional food unless it has been “gut-loaded” and even then I have my doubts. Newly hatched “baby” Brine Shrimp is excellent for fry (if you can afford it!). Adults will eat it, but since it is so small I don’t think it’s filling enough for larger Corys. Also, once baby Brine is hatched it should be fed off within half a day or it loses most of its nutritional value. Remember to soak, or at least rinse it off, in freshwater before feeding.
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