I have kept tetras and algae eaters with D. galactonotus darts in a 135 gallon paludarium now for going on 8 years, and it's worked out better than any plain tropical fish tank I've ever tried to keep. Some of the original tetras are still with me, and darts can certainly swim and climb out, even up glass, if necessary, but it's best to have a submerged log leading to the bank. Now that there are a lot of floating leaves in the aquarium portion, my galacts spend a lot of time on the water nabbing the fruit flies that fall in.
While some darts, such as the tinctorius that are territorial and fight have been reported to drown one another in shallow water by holding one under, in a deeper tank, they just can't do this because thay can't get a purchase, and both frogs will be forced to separate and swim away.
I also have a deep water pond in one of my D. imitator tanks, and have seen these dive in on occasion, and even submerge for awhile when they are frightened by something. This isn't their usual habit, however.
I think if you chose one of the more gregarous frogs such as leucomelas, galactonotus, terribilis, or the imitators, you should have no trouble mixing with small fish like the tetras in an aquarium section.
I have tried plays and other small fish, but the tetras such as the X-rays, rummy nose, head and tail light do just fine. I also have a yoyo loach to control snails that has survived for two years, now.
I have divided the land and water portions with vertical glass, cut to fit, so the aquarium part is not part of a false bottom into which water drains from the terrarium part, which has its own drainage layer that I siphon off occasionally.
There is a deep pool on the right, (12"
then this flows over a short barrier of glass into a front river run at about 10 inches deep, then into a lagoon that goes all the way to the back and another narrower section that leads to the pump on the left. The pump circulates the water back over two water falls, one into the lagoon and the other into the far pond. This aerates and filters the water, as the rock falls are now colonized with Java moss and the tubing and falls are also colonized with nitrifying bacteria. It is heavily planted with aquarium plants and Java. I have never done a complete take-down of the aquarium, only partial water changes and adding water for evaporation.
I've shown this photo many times here. It was taken when the paludarium was first set up, and I really need to get some new ones of it 8 years later, because it looks so much better now. However, it will give you an idea. There are also some more recent pictures of the galacs fishing and playing in the water.



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Patty
Pahsimeroi, Idaho
4 D. auratus blue
6 D. galactonotus pumpkin orange splash back
7 D. imitator
6 D. leucomelas
6 D. pumilio Bastimentos
4 D. fantasticus
6 P. terribilis mint and organe
4 D. reticulatus
4 D. castaneoticus
2 D. azureus
4 P vittatus
2 P. lugubris