I was doing a 20% weekly water change on some my tanks today (we have 10 in all) and noticed a worrisome creature. This tank is a 55 gallon planted tank, with three 5-6 inch goldfish, a weather loach, and several siamese algae eaters. One of the goldfish was attacked about 2 weeks ago by a pleco, that has since been re-homed in another tank. This fish is still recovering, and lost about 20% of his scales on his tail area. He's looking pretty rough, but eating OK. The other two fish are doing fine.
The critter reminded me of a leech. I ran into several of these while vacuuming the gravel. They were tan colored, between 3/8 and 3/4 inch long (depending on individual.) When sucked into the vacuum tube (the larger diameter tube), they'd try to cling to the side of the tube, and eventually, lose strenth and let go. I'm not sure, but I think that the creature was triangularly shaped (cross section.) The diameter of the worm (for lack of a better word) was about the same as the diameter of a pin, but that did change as the worm contracted and elongated.
Several things come to mind and need to be mentioned.
1. I have two other goldfish tanks, another 55 and a 125. Did not see any of the critters in the other tanks. These are planted too.
2. I have not seen the creatures attached to the fish. I even looked in the gills.
3. My three goldfish tanks have been "off" for about two months. I have attributed the problem to the purchase of 4 fish, 3 of which have died. 3 of my other beautiful fish have died too, though I did think I was through the worst of it. The fish seemed to improve a great deal after treatment with praziquantel. They still don't seem quite as frisky and happy as they should.
4. My hope is that the creature may well be harmless, and could have arrived as a hitchhiker along with some plants.
BUT - I sure don't want to be ignoring something that needs treatment.
Any ideas out there?
125, 20L, 2 29H, 4 10, 3 55, 1 40
All planted. 125, 40, and 2 55 very fancy goldys
55, 29, 2 10's tropicals and livebearers
2 10's guppies
20L, 29 high light, soil, DIY CO2, high planted, tropicals, Angels, loaches, gouramis, barbs etc.