Knowledge Base

Problem

When using the DanioVision to observe nematodes (e.g., C. elegans) rather than zebrafish larvae, the animals remain unclear or too small to track reliably even after adjusting the camera focus.

Details

Symptoms: Animals are not sharply resolved and standard detection parameters in EthoVision XT cannot be achieved. The standard fixed-focus DanioVision lens is optimised for zebrafish larvae in a 24-well plate and does not provide sufficient magnification or working distance adjustment for nematodes. Adjusting the built-in focus ring alone is insufficient.

Solution

1. Replace the standard DanioVision lens with an adjustable-focus lens that provides greater magnification suitable for nematodes. Contact Noldus support or your regional representative to identify compatible lens options.
2. To adjust the working distance so the nematode dish is within the new lens's focal range, place the dish on a transparent (e.g., acrylic/glass) lifting platform to raise it closer to the camera.
3. After making these adjustments, fine-tune the focus ring on the new lens until the nematodes are as sharp as possible.
4. Adjust detection settings in EthoVision XT (subject size, contrast threshold) to suit the nematode body size.
5. Note: even with these modifications, results may not fully meet standard DanioVision performance parameters for nematodes — validate your specific protocol before running experiments.
6. Contact Noldus support if you require further guidance on validated protocols for non-zebrafish organisms.