The Puffer Forum

just wanted to find out if the little white worms i see on my tank glass are beneficial or harmful and what the heck they are exactly. they were in the 30g brackish with my 3 f8s and when i moved everything over from that tank to the 75g they seem to have made the trip with them. they are the width of a human hair and only a few millimeters long very very tiny. thanks for any responses.

Without a photo or tank parameters, it's hard to be precise -- but I'd venture a guess that they're planaria. Very common in tanks with high bioload (overfeeding, too much waste, etc.). Harmless to fish, but to get rid of them, you'll want to make sure that all food is consumed by your puffs and perhaps step up the % of your water changes.

Planaria are not that slender, nematodes are more likely from that description.

Both of those inverts are normal tank inhabitants, but are rarely seen. If they are present in large numbers and thus readily visible it is generally a result of of excessive organics, especially in the substrate, but also in the water column.

The correction or cure is improved tank upkeep with full depth vacuuming and 50% weekly partials. Doing alternate day 50% partials should correct the issue in a week. After that you can go back to regular 50% partials with full depth vacuuming once a week.

Too deep substrates and insufficient care result in excessive planaria and nematodes. They feed on the microbes and infusoria which feed on the organics.

i just moved them to this freshly filled tank a week ago the tank params are all good. nematodes arent harmful are they?

Nematode species are very difficult to distinguish; over 28,000 have been described,[1] of which over 16,000 are parasitic. ^ Hugot et al. (2001)

But you will never see parasitic nematodes free-swimming in a tank. If you have an excess of nematodes or planaria, they are harmless but indicate excessive organics in the tank water/substrate. We cannot measure the organic load in our tanks.