I've been around almost a year, and I also can't really think of situations where people have recommended them. I don't even know which fish benefit from dither fish - well, except BGKs, since Jaysee just explained that.
Hiding places definitely help but with adults in the tank it is inevitable that at least some fry will get eaten.
As for the sanctuary box I don't actually breed live bearers anymore so I don't have one laying around to snap a picture of (I just hatch my eggs off in a separate tank) but I'm sure you've seen a net breeder box. Imagine that (albeit larger) with wire mesh encompassing all sides (including top and bottom).
With wire mesh that is thick enough it's very easy to bend some into shape (doesn't necessarily have to be a cube...). Just weigh down the bottom so it isn't floating around.
Basically you're adding a lid to a breeder box and replacing the netting with wire mesh. If you used two stacked on top of each other as the "bones" of the contraption it would probably be big enough. Even just one would do in a smaller tank but the bigger the better.
I don't have any input on dither fish, but for your fry, I suggest water sprite. I find it makes an excellent plant for fry to hide in and my molly fry also spend a lot of time eating from it as well. It will provide cover in all levels of the tank, especially the mid-upper levels which I'm guessing the java moss and guppy grass doesn't provide protection in those areas. It is a super easy plant to grow IME.
Why would a dither fish prevent the fry from being eaten? It's just more hungry mouths in a tank with bite sized snacks.
I've always seen dither fish described as either a fish that will draw a shy fish into the open (ie if its safe out there for them it's safe for me) or a fish to curb aggression (ie the aggressive fish wastes time and energy chasing them to cut down on the time and energy available to harass other tank mates).
Neither of those would apply to fry. The more mouths they can fit into the more mouths they will end up in.
Any fish small enough to fit into another fishes mouth will be breakfast. That's just the way it is.
You could try adding some Dwarf Water Lettuce to float on top of the water. Once the roots get long, it makes for a good hiding spot for fry:
View attachment 118793View attachment 118794
Photos above are of my pond, a haven for cute little frogs. No fish.
Check your local fish stores and Fish Lore Buy/Sell/Trade/Free for Dwarf Water Lettuce.
I added a few sprigs of the Dwarf Water Lettuce in the early spring and it's growing like crazy! I also keep it in my 33g tank and 4 refugiums. You can see how large the lettuce is when given a lot of space and lots of light. The pond gets full sun from around noon to late evening.
Sorry, I do not ship. Privacy reasons.
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Note the roots hanging down from the Dwarf Water Lettuce.
The heterandria formosa are also livebearers and can probably cross with the guppies.
In my guppies' tank I have a lot of hornwort floating around--it takes up probably 1/3 of the tank. I'm sure I lose some babies but, as you know from my post in the RAOK, I have several who do not get eaten. I usually leave them in the parent's tank for at least a week, basically until they are big enough to NOT be eaten, then I move them to the baby tank.
What kind of snails do you have? My 45g is heavily planted and the majority of the plants are water sprite. That tank has bladder, ramshorn, trumpet, and assassin snails and none of them eat the plants. The bladders chewed some holes in my anubias and sword leaves, but they don't bother the water sprite.
I believe they breed pretty commonly, but they are good parents and one may be killed if there isn’t a fish to give them a sense of the need to protect there babies. They are also shy so it helps to have a fish that is out to bring them out and show it’s somewhat safe. Are pencil fish fast moving if they need to?Hi Jallen42
It would seem the name dither fish can be used for a fish doing two different jobs?
If a dither fish is to show the water is safe and the other fish can come out now ? Then a top water fish does that job.
If a dither fish is there to take any aggression that might otherwise be put on the parter in a pair breeding situation then that is a different job. A fast moving fish is required.
I believe the pencil fish can do both of these jobs.
My pencil fish have not read that they should stay in the top of the tank. Their mouths are small making them an excellent choice for a dither fish IMO. I have pencil fish with other dwarf cichlids but I have not kept Kribs . I believe they breed often?
I may have to avoid pencil fish unfortunately unless they do fine in harder water! I may still try them cause they may adapt as the ones I can get are captive bred!Pencil fish have the torpedo shape of a fast moving species. I believe it should be a good combination?
I also had that idea I just wasn’t sure if the guppies I like “panda guppies” would be a good option for that, however with my harder water I believe I am gonna get some Julis .What about guppies [that's what I use], a 20 would be fine, it's what I use for breeding kribs, good luck