Conservation Evidence strives to be as useful to conservationists as possible. Please take our survey to help the team improve our resource.

Providing evidence to improve practice

Action: Create walls or barriers to exclude pollutants Amphibian Conservation

Key messages

Read our guidance on Key messages before continuing

  • One controlled study in Mexico found that installing filters across canals to improve water quality and exclude fish increased weight gain in axolotls.


Supporting evidence from individual studies


A controlled study in 2009 of canals within agricultural land in Xochimilco, Mexico (Valiente et al. 2010) found that installing filters to improve water quality and exclude competitive fish increased weight gain in axolotls Ambystoma mexicanum. Only four of 12 previously marked axolotls were recaptured; however, their weight had increased by 16%. Weight gain was greater than that of axolotls in control colonies over the same period. After four months, water was significantly lower in ammonia (77%), nitrates (87%) and turbidity (15%) compared to control canals. Working with farmers in 2009, a canal used as a refuge by axolotls was isolated from the main system using filters made of wood to exclude fish and improve water quality. Farmers benefited from improved farm products with the improved water quality and the protection of traditional agriculture.


Referenced papers

Please cite as:

Smith, R.K., Meredith, H. & Sutherland, W.J. (2019) Amphibian Conservation. Pages 9-65 in: W.J. Sutherland, L.V. Dicks, N. Ockendon, S.O. Petrovan & R.K. Smith (eds) What Works in Conservation 2019. Open Book Publishers, Cambridge, UK.