主に琵琶湖の固有種であるニゴロブナが使用される。

Nigoro buna (Carassius auratus grandoculis) which is an indigenous species of Lake Biwa is mainly used. - Wikipedia日英京都関連文書対訳コーパス

4月頃、ニゴロブナ（他のフナで代用も可）のウロコとエラを取り、腹開きにして卵巣以外の内臓を除く。

The season for funa-zushi begins around April, and to make it you first remove the scales and gills from some nigoro buna (other crucian carp varieties can be used as substitutes) and then split its belly to gut it, keeping the ovaries, if present, intact. - Wikipedia日英京都関連文書対訳コーパス

近年、手間と時間のかかる製法であることや、材料として最も適する種類のフナであるニゴロブナが湖岸のヨシ原減少や水質の悪化、湖岸のコンクリート護岸化にともなう産卵床破壊、外来魚などにより減少していることで価格が1尾数千円と高騰し、ゲンゴロウブナやギンブナを代用したものも作られている。

Due to its time-consuming and labor-intensive recipe and the dwindling number of funa and nigoro buna, that are most suitable for making funa-zushi, caused by various factors including the decreased reed fields, deteriorating water quality, destruction of breeding grounds by concrete embankment and fish of foreign origin in the lake, the price of these fish species has steeply risen to several thousands of yen each in recent years and, in some cases, funa-zushi is made with gengoro buna (Carassius cuvieri) and gin buna (Carassius langsdorfii) in substitution for funa and nigoro buna. - Wikipedia日英京都関連文書対訳コーパス