Sailfinmollies

Question
I have a pond of about 3 thousand liters of water which I am breeding sailfinmollies in. The water is of good quality hard with a GH of about 150 PH of around 8. I feed them two to three times a day with good food based on vegetable matter. Some times I get peas and cook them up and crush them up into a paste.I feeel the babies dont seem to be growing as quick as I want them too. Is it possible the water is to clear for them and not enough green matter growing in pond. I have a bio logical filter on the pond and UV steriliser aswell.

Answer
Hi Roy,

Everything sounds great, I'm sure your fish are healthy and happy! The way to grow out fry quickly is to take a cue from discus breeders - up the protein content of the feed, and change lots of water. How much water you change is up to you - try to flush the pond at least monthly. Topping up for evaporation in a pond instead of flushing tends to make a high concentration of nitrates (and other undesirable things we cannot test for, such as growth inhibiting/limiting hormones). Using lots of plants helps to keep nitrates 0 ppm. Any kind of fast growing floating plant (not sure what to recommend for Australia) will do the trick, but you should still flush the water even if you see 0 ppm of nitrates.

Pond flakes and pellets tend to be very low in protein. I have seen some as low as 22%. Standard vegetarian fish flake usually has 36-40% protein at the lowest, so you see the difference. While mollies can do just fine on a low protein, entirely green diet, to get the fry to grow faster, I would supplement with some meaty foods. Instead of making a paste based on peas only, try mixing in shrimp (prawns) - leaving the shells on is best. Grind them up in a food processor and add them to the pea based feed. You can also add Spirulina powder, which adds protein (algae based, so not harmful to mollies). Instead of shrimp you can use seafood mix also, which tends to be more economical and gives you lots of variety. You can Google "European shrimp mix" for more information.

Algae is definitely beneficial to fry, so whatever you can do to encourage it is recommended. The UV sterilizer is probably making it difficult to grow algae in your main pond - maybe you could set up a separate, smaller pond just for harvesting algae in. Maybe take some floating plants, grow them in a "kiddie pool", and put them in water with some aquarium fertilizer (such as Flourish) added to it. This should grow algae amidst the leaves and/or roots, which the molly fry could graze on.

I hope that helps! Take care.
Nicole