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Aim Ecological niche models (ENMs) are widely used to address urgent real‐world problems such as climate change effects or invasive species; however, the generality of models when projected through space and/or time, that is transferability, remains a key challenge. Here, we explored the effects of complex predictors and feature selection on ENM transferability in a widely employed algorithm, Maxent, using five globally invasive freshwater species as case studies. Location Global. Methods We modelled the global distributions of five notorious freshwater invasive species (African sharptooth catfish Clarias gariepinus, Mozambique tilapia Oreochromis mossambicus, American bullfrog Lithobates catesbeianus, red swamp crayfish Procambarus clarkii, and Australian redclaw crayfish Cherax quadricarinatus), using three predictor datasets of varying complexities derived from two commonly used climatic data sources (WorldClim and IPCC) and three methods of model tuning that differentially incorporated feature selection. Spatially explicit transferability assessments were then conducted using a suite of evaluation metrics previously used to quantify Maxent model performance. Results We show that in the absence of detailed biological knowledge of focal species, simpler predictor datasets produce models that are more accurate than those calibrated using comprehensive “bioclimatic” datasets. Additionally, we find that tuning models for both optimal regularization parameters as well as feature‐class combinations led to the greatest increases in transferability and geographic niche conservatism. Results indicate a tenuous link between model transferability and Akaike's information criterion corrected for small sample sizes (AICc), suggesting that the indiscriminate use of AICc as an estimate of model parsimony may lead to erratic model performance. Main conclusions Our findings demonstrate that methodological considerations can drastically affect the reliability of spatial and possibly temporal projections, which has severe implications when ENMs are used to infer species’ niches, and quantify ecological or evolutionary change across impacted landscapes.

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Bukit Timah Nature Reserve (BTNR) holds the largest remnant patch of primary rainforest in Singapore and its hill streams supports many native and threatened freshwater fauna. As the last comprehensive survey of freshwater fishes in BTNR was published nearly two decades ago, a series of surveys was carried out at 12 streams permeating BTNR and the Singapore Quarry to update the status of the fishes. Of the 27 species documented, 16 are native to Singapore and 11 are introduced. Two native species known from other parts of the Central Catchment Nature Reserve are recorded for the first time in BTNR. Species distribution, richness and abundance have been qualitatively assessed in relation to habitat characteristics. Potential threats and mitigation measures are discussed, which are important in the formulation of conservation and management strategies to safeguard the current diversity of freshwater fishes, many of which are threatened in rapidly developing Singapore.

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