Fish breeding: It's about control. Or, is it?

For those of you who breed tropical fish, the idea of electing your breeders, setting up a dedicated aquarium for them, conditioning them with food, etc. is part of a dedicated process- one which we as humans-fish geeks- have a certain degree of control over.

I was talking not too long ago with a fellow hobbyist who's been trying all sorts of things to get a certain Loricarid catfish to spawn. He's a very experienced aquarist and has bred many varieties of fishes...but for some reason, this one is just vexing to him! I suppose that's what makes this hobby so damn engaging, huh?

And maddening at times, too!

And of course, I was impressed by all of the efforts he's made to get these fish to spawn thus far...I mean, he was trying shit I've never even thought of! Talk about dedication! Yet, I kept thinking that there must be something fundamental-something incredibly simple, yet incredibly important- that he was somehow overlooking...

It's intriguing.

I mean, what is that "thing"- or set of "things" which make fishes spawn- or not- despite, or without, our best efforts?

Are there simply some factors which we cannot manipulate to affect spawning in some fishes? What makes some fishes "easy" to spawn, and others tantalizingly difficult?

When I travel around the country on speaking engagements or whatever and have occasion to visit the fish rooms of some talented hobbyists, I never cease to be amazed at what we can do when it comes to fish breeding!

We do an amazing job.

And of course, being the thoughtful type, I always wonder if there is some way we can do it better....If there is some key thing we're missing that can help us do even better.

We do so much so well already.

Now, I realize that most of us like to keep things controlled to a great extent- to be able to monitor the progress, see where exactly the fishes deposit their eggs, and to be able to remove the eggs and fry if/when needed.


I mean, we strive to create the water conditions (i.e.; temperature, pH, current, lighting, etc.) for our fishes to affect spawning, but we tend to utilize more "temporary" type, artificial-looking setups with equipment to actually facilitate egg-laying, fry rearing, etc.

Purely functional.

Now, I realize that it's long been thought that more rapid environmental changes will trigger spawning in certain fishes, like Corydoras. We have known for some time that changes in environmental parameters really stimulate these fish...

And, of course, we use this to our advantage as aquarists by manipulating temperature and such within our aquariums. My understanding is that some of these changes replicate stuff like "rain storms", "Cold fronts", seasonal changes, etc. Stuff that we've been advocating in a different way with our "Urban Igapo" idea, right?

I often wonder what is wrong with the idea of a permanent setup- a setup in which the fishes are provided a natural setting, and left to their own devices to "do their thing..."

This is pretty much the "classic" way many of us "bred" livebearers, killifish, and Rainbowfishes for a long time. It's a very low-labor, aesthetically interesting way to keep and breed these guys.

Now, I realize that a lot of hardcore, very experienced breeders will scoff at this- and probably rightly so. For the serious breeder, giving up control when the specific goal is the reproduction of your fishes is probably not a good thing. Practicality becomes important- hence the employment of clay flowerpots, spawning cones, breeding traps, bare tanks to raise fry, etc.

Sure, to a fish, a cave is a cave, be it constructed of ceramic or if it's the inside of a hollowed-out Cariniana pod. To the fish, it's a necessary place to spawn quietly and provide a defensible territory to protect the resulting fry. In all likelihood, they couldn't care less what it is made of, right? And to the serious or professional breeder, viable spawns are the game.

I get that.

I guess my personal approach to fish breeding has always been, "If it happens, great...If not, I want the fishes to have an environment that mimics the one they're found in naturally." And that works to a certain extent, but I can see how many hobbyists feel that it's certainly not the practical way to do systematic, controlled breeding. I mean, can you imagine how weird the availability of tropical fishes would be in the hobby if we simply "let them do their own thing?" Yeah, that wouldn't work.

I get, THAT, too.

Yet, isn't their something wonderful (for those of us who are not hell-bent on controlling the time and place of our fish's spawnings) to check out your tank one night and see a small clutch of Apistogramma fry under the watchful eye of the mother in a Sterculia Pod or whatever? Perhaps not as predictable or controllable as a more sterile breeding tank, but nonetheless, exciting!

And of course, to the serious breeder, it's just as exciting to see a bunch of wriggling fry in a PVC pipe section as it is to see them lurking about the litter bed in the display tank.

I suppose it's all how you look at it.

No right or wrong answer.

The one thing that I think we can all agree with is the necessity and importance of providing optimum conditions for our potential spawning pairs. There seems to be no substitute for good food, clean water, and proper environment. Sure, there are a lot of factors beyond our control, but one thing we can truly impact is the environment in which our fishes are kept and conditioned.

And the environment in which the resulting fry are reared.

So, like many things in the hobby- the approaches to spawning fishes may have changed over the years, but the idea remains the same- using whatever means we have at our disposal to create the best possible outcomes for our fishes!

So, what is wrong with the idea of "permanent" setups for some of us in our efforts?

Nothing, really.

Now, no discussion of rearing our little fishes would be complete without revisiting the idea of a botanical-influenced "nursery" tank for fishes. You know where I'm going with this, no right?

I think it's interesting for a number of reasons:

First, as we've discussed many times, the humic substances and other compounds associated with leaves and other botanicals, when released into the water, are known to have beneficial health impact on fishes. The potential for antimicrobial and antifungal effects is documented by science and is quite real.

Wouldn't this be something worth investigating from our unique angle? 

I think so!

Additionally, rearing young fishes in the type of environmental conditions under which they will spend the rest of their lives just makes a lot of sense to me. Having to acclimate young fishes into unfamiliar/different conditions, however beneficial they might be, still can be stressful to them.

So, why not be consistent with the environment from day one?

Wouldn't a "botanical-style fry-rearing system", with it's abundant decomposing leaves, biofilms, and microbial population, be of benefit?

I think so.

This is an interesting aspect of botanical-style aquariums; we've discussed it before- the idea of "on board" food cultivation for fishes.

The breakdown and decomposition of various botanical materials provides a very natural supplemental source of food for young fishes, both directly (as in the case of fishes such as wood-eating catfishes, etc.), and indirectly, as they graze on algal growth, biofilms, fungi, and small crustaceans which inhabit the botanical "bed" in the aquarium.

Now, this is pretty interesting stuff to me!

I know- everyone has their own style of fry rearing- controlled or otherwise.

Some hobbyists like bare bottom tanks, some prefer densely planted tanks, etc., and there are valid reasons for each, of course. 

I'm proposing the idea of rearing young fishes in a botanical-style aquarium with leaves, some seed pods, and maybe some plants as well. This type of aquarium physically and "functionally" mimics, at least to some extent, the habitats in which many young fishes grow up in.

My thinking is that decomposing leaves will not only provide material for the fishes to feed on and among, they will also provide a natural "shelter" for them as well, potentially eliminating or reducing stresses.

In nature, many fry which do not receive parental care tend to hide in the leaves, substrate, or other biocover in their environment, and providing such natural conditions will certainly accommodate this behavior.

And of course, decomposing leaves can stimulate a certain amount of microbial growth, with infusoria, forms of bacteria, and small crustaceans, becoming potential food sources for fry. I've read a few studies where phototrophic bacteria were added to the diet of larval fishes, producing measurably higher growth rates. Now, I'm not suggesting that your fry will gorge on beneficial bacteria "cultured" in situ in your blackwater nursery and grow exponentially faster.

However, I am suggesting that it might provide some beneficial supplemental nutrition at no cost to you!

I've experimented with the idea of "onboard food culturing" in several aquariums systems over the past few years, which were stocked heavily with leaves, twigs, and other botanical materials for the sole purpose of "culturing" (maybe a better term is "recruiting) biofilms, small crustaceans, etc. via decomposition.

I have kept a few species of small characins in these systems with no supplemental feeding whatsoever and have seen these guys as fat and happy as any I have kept.

And it's the same with that beloved aquarium "catch all" of infusoria that we have talked about before here...These organisms are likely to arise whenever plant matter decomposes in water...And in an aquarium with significant leaves, botanical materials, and such, there is likely a higher population density of these ubiquitous organisms available to the young fishes, right?

Now, I'm not fooling myself into believing that a large bed of decomposing leaves and botanicals in your aquarium will satisfy the total nutritional needs of a batch of characins, and that you won't have to do anything else- but it might provide the support for some supplemental feeding!

Perhaps, significant, actually.

On the other hand, I've been playing with this recently in my "varzea" setup, stocked with a rich "compost" of soil and decomposing leaves, rearing the annual killifish Notholebias minimus "Campo Grande" with great success.

It's essentially an "evolved" version of the "jungle tanks" I reared killies in when I was a teen. A different sort of look- and function! The so-called "permanent setup"- in which the adults and fry typically co-exist, with the fry finding food amongst the natural substrate and other materials present I the tank. Or, of course, you could remove the parents after breeding- the choice is yours.

I'd take the concept even a bit further by "seeding" the tank with some Daphnia and perhaps some of the other commonly available live freshwater crustaceans, and letting them do their thing before the fry arrive. This way, you've got sort of the makings a little bit of a "food web" going on- the small crustaceans helping to feed off of some of the available nutrients and lower life forms, and the fish at the top of it all. 

Now, granted, I'm truly "romancing" this and perhaps even over-simplifying it a bit. However, I think that there is a compelling case to be made for creating a rearing tank that supports a biologically diverse set of inhabitants for food sources.

The basis of it all would be leaves and some of the botanicals which seem to do a better job at recruiting biofilms- the "harder shelled/surfaced" stuff, like  Jackfruit leaves, Yellow Mangrove leaves, Guava Leaves, Carinaina Pods, Dysoxylum pods, etc...I think these would be interesting items to include in a "nursery tank." And of course, they provide shelter and foraging areas and impart some tannins into the water...the "usual stuff."

On the other hand, we DO control the environment in which our fishes are kept- regardless of if the tank looks like the bottom of an Asian stream or a marble-filled 10-gallon, bare aquarium, right?

I just wonder...being a lover of the more natural-looking AND functioning aquarium, if this is a key approach to unlocking the spawning secrets of more "difficult-to-spawn" fishes. Not a "better spawning cone" or breeding trap, or more enriched brine shrimp, mind you. Rather, a wholistic approach featuring excellent food, optimum natural water conditions, and a physical environment reminiscent of the one they evolved in over millennia.

Won't the fishes "figure it all out?"

I think so!

And, I wonder if fry-rearing tanks can- and should- be "natural" setups, too- even for serious breeders. You know, lots of plants, botanical cover, whatever...I mean, I KNOW that they can...I guess it's more of a question of if we want make the associated trade-offs? Sure, you'll give up some control, but I wonder if the result is healthier, more vigorous young fish?

It's not a new idea...or even a new theme here in our blog.

However, I think that, in our intense effort to achieve the results we want, we occasionally will overlook something as seemingly basic as this.

I certainly know that I have.

And I think that our fishes will let us know, too...I mean, those "accidental" spawnings aren't really "accidental", right? They're an example of our fishes letting us know that what we've been providing them has been exactly what they needed.

It's worth considering, huh?

Nature has a way.

It's up to us to figure out what it is. Be it with a ceramic flower pot or pile of botanicals...

It might not be all about control of every aspect...

And that certain "lack of control"- that "ceding" of some of the work to Nature. Having trust in Her- may be exactly what our fishes need?

Stay diligent. Stay persistent. Stay curious. Stay determined. Stay driven. Stay observant...

And Stay Wet.


Scott Fellman

Tannin Aquatics 






Scott Fellman
Scott Fellman


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